Method of making barrier layers

ABSTRACT

The present invention involves a low-temperature, photoresist-free method of fabricating a barrier layer on a flexible substrate. An embodiment involves the conversion of a precursor into a top-surface imaging layer during a direct patterning step. Preferred precursors are formed from a metal complex comprising at least one ligand selected from the group consisting of acac, carboxylato, alkoxy, azide, carbonyl, nitrato, amine, halide, nitro, and mixtures thereof and at least one metal selected from the group consisting of Li, Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Ba, La, Pr, Sm, Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As, Ce, Mg, and mixtures thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation-in-part of copending application Ser. No.09/875,115 to Maloney et al., published as U.S. Ser. No. 2002/0076495,that was filed Jun. 6, 2001 and is entitled “Method of Making ElectronicMaterials,” which claims priority to provisional application no.60/209,947, filed Jun. 6, 2000, both of which are hereby incorporated byreference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to improved organicelectroluminescent devices and improved methods for manufacturingorganic electroluminescent devices. In particular, the present inventionrelates to improved method of forming a barrier layer in such devicesusing a photochemical metal organic deposition process. An embodimentinvolves the direct photolytic conversion of a precursor materialdeposited over a substrate to act as a barrier layer.

[0003] Organic electroluminescent devices include organic light-emittingdiodes and polymer light-emitting diodes. They are used in a number ofdevices, such as car radios, mobile phones, digital cameras, camcorders,personal digital assistants, and other devices using flexible andnon-flexible displays.

BACKGROUND OF THE INVENTION

[0004] The semiconductor and packaging industries, among others, utilizeconventional processes to form thin metal and metal oxide films in theirproducts. Examples of such processes include evaporation, sputterdeposition or sputtering, chemical vapor deposition (“CVD”) and thermaloxidation. Evaporation is a process whereby a material to be depositedis heated near the substrate on which deposition is desired. Normallyconducted under vacuum conditions, the material to be depositedvolatilizes and subsequently condenses on the substrate, resulting in ablanket, or unpattemed, film of the desired material on the substrate.This method has several disadvantages, including the requirement to heatthe desired film material to high temperatures and the need for highvacuum conditions. Unless a screen or shadow is employed duringevaporation, an unpattemed, blanket film results from this process.

[0005] Sputtering is a technique similar to evaporation, in which theprocess of transferring the material for deposition into the vapor phaseis assisted by bombarding that material with incident atoms ofsufficient kinetic energy such that particles of the material aredislodged into the vapor phase and subsequently condense onto thesubstrate. Sputtering suffers from the same disadvantages as evaporationand, additionally, requires equipment and consumables capable ofgenerating incident particles of sufficient kinetic energy to dislodgeparticles of the deposition material.

[0006] CVD is similar to evaporation and sputtering but further requiresthat the particles being deposited onto the substrate undergo a chemicalreaction during the deposition process in order to form a film on thesubstrate. While the requirement for a chemical reaction distinguishesCVD from evaporation and sputtering, the CVD method still demands theuse of sophisticated equipment and extreme conditions of temperature andpressure during film deposition.

[0007] Thermal oxidation also employs extreme conditions of temperatureand an oxygen atmosphere. In this technique, a blanket layer of anoxidized film on a substrate is produced by oxidizing an unoxidizedlayer which had previously been deposited on the substrate.

[0008] Several existing film deposition methods may be undertaken underconditions of ambient temperature and pressure, including sol-gel andother spin-on methods. In these methods, a solution containing precursorparticles that may be subsequently converted to the desired filmcomposition is applied to the substrate. The application of thissolution may be accomplished through spin-coating or spin-casting, wherethe substrates is rotated around an axis while the solution is droppedonto the middle of the substrate. After such application, the coatedsubstrate is subjected to high temperatures which convert the precursorfilm into a film of the desired material. Thus, these methods do notallow for direct imaging to form. patterns of the amorphous film.Instead, they result in blanket, unpatterned films of the desiredmaterial. These methods have less stringent equipment requirements thanthe vapor-phase methods, but still require the application of extremetemperatures to effect conversion of the deposited film to the desiredmaterial.

[0009] In one method of patterning blanket films, the blanket film iscoated (conventionally by spin coating or other solution-based coatingmethod; or by application of a photosensitive dry film) with aphotosensitive coating. This photosensitive layer is selectively exposedto light of a specific wavelength through a mask. The exposure changesthe solubility of the exposed areas of the photosensitive layer in sucha manner that either the exposed or unexposed areas may be selectivelyremoved by use of a developing solution. The remaining material is thenused as a pattern transfer medium, or mask, to an etching medium thatpatterns the film of the desired material. Following this etch step, theremaining (formerly photosensitive) material is removed, and anyby-products generated during the etching process are cleaned away ifnecessary.

[0010] In another method of forming patterned films on a substrate, aphotosensitive material may be patterned as described above. Followingpatterning, a conformal blanket of the desired material may be depositedon top of the patterned (formerly photosensitive) material, and then thesubstrate with the patterned material and the blanket film of thedesired material may be exposed to a treatment that attacks the formerlyphotosensitive material. This treatment removes the remaining formerlyphotosensitive material and with it portions of the blanket film ofdesired material on top. In this fashion a patterned film of the desiredmaterial results; no etching step is necessary in this “liftoff”process. However, the use of an intermediate pattern transfer medium(photosensitive material) is still required, and this is a disadvantageof this method. It is also known that the “liftoff” method has severelimitations with regard to the resolution (minimum size) that may bedetermined by the pattern of the desired material. This disadvantageseverely limits the usefulness of this method.

[0011] It is thus evident that the deposition of blanket films that needsubsequently be patterned invokes the need for several extra costly anddifficult processing steps.

[0012] In yet another method of forming patterned films, a blanket filmof desired material may be deposited, e.g., by one of the methodsdescribed above, onto a substrate-that has previously been patterned,e.g., by an etching process such as the one described previously. Theblanket film is deposited in such a way that its thickness fills in andcompletely covers the existing pattern in the substrate. A portion ofthe blanket film is then isotropically removed until the remainingdesired material and the top of the previously patterned substrate sitat the same height. Thus, the desired material exists in a patternembedded in the previously patterned substrate. The isotropic removal ofthe desired material may be accomplished via an etching process;commonly in the case of the formation of semiconductor devices it isenvisioned that this removal is effected through a process known aschemical mechanical planarization (“CMP”). This involves the use of aslurry of particles in conjunction with a chemical agent to removesubstantial quantities of the desired material through a combination ofchemical and mechanical action, leaving behind the desired material inthe desired places embedded in the patterned substrate. This method offorming a patterned film demands the use of expensive and complicatedplanarization equipment and extra consumable materials includingplanarization pads, slurries and chemical agents. In addition, the useof small slurry particles demands that these particles be subsequentlyremoved from the planarized surface, invoking extra processing steps.

[0013] While some of these methods are more equipment-intensive thanothers and differ in the use of either solution- or vapor-phase methods,such conventional processes for forming metal and metal oxide films isnot optimal because, for example, they each require costly equipment,are time consuming, require the use of high temperatures to achieve thedesired result, and result in blanket, unpatterned films where, ifpatterning is needed, further patterning steps are required. Many ofthese methods suffer the additional disadvantage of, in many cases,forming polycrystalline films which may not be suitable for a variety ofapplications. A desirable alternative to these methods would be the useof a precursor material that may be applied to a substrate andselectively imaged and patterned to form an amorphous film without theneed for intermediate steps.

[0014] One use of thin films in semiconductor processing is for theformation of thin top-surface imaging (hereafter “TSI”) layers,typically atop organic layers that have already been applied to thesubstrate. In this instance, the organic layer need not be photoactive,since the thin film to be deposited will be subsequently patterned usingconventional methods. The use of these thin films for TSI confersseveral process advantages, including resistance to plasma etching notafforded by the use of photoresist masks, and the increased resolutionof the lithographic process afforded by a very thin film. Typical thinfilms for TSI include metal and silicon nitride and oxide films, and agreat deal of research has also been conducted on a process known assilylation. This process involves the vapor deposition of a thin film ofa silicon-containing species on top of a previously deposited organiclayer. This thin film of the silicon species can then be imaged to forma thin film of silicon oxide, which acts as the TSI layer duringoxygen-plasma patterning of the organic layer beneath. The acceptance ofsilylation processes by the semiconductor and packaging industries hasbeen insignificant as a result of a number of process and costlimitations.

[0015] Another use of thin films in semiconductor processing is for theformation of hard masks, e.g., for use in ion implantation processing.Ion implantation is a well known technique used, for example, in formingdoped regions in a substrate during semiconductor fabrication. Ionimplantation frequently requires a patterned blocking layer, also knownas a hard mask, which directs the ions to be implanted only intopredetermined regions. For example, U.S. Pat. No. 5,436,176 to Shimizuet al. discloses, in “Embodiment 1”, maskless implantation of a siliconsubstrate covered by a silicon oxide film, which is disclosed to bethrice-implanted with boron atoms. Alternatively, the same patentdiscloses, in “Embodiment 3”, implantation using multiple hard masks ina thrice-repeated method comprising the following sequence of steps:forming a mask on a silicon substrate covered by a silicon oxide film,implantation with phosphorus, forming a second mask, implantation withboron, and, finally, annealing.

[0016] As previously discussed, formation of a hard mask by any of theseprocesses requires a relatively large number of processes steps.Eliminating some of these steps before etching or ion implantation wouldbe beneficial because, for example, it would simplify the process used,increase its efficiency and reduce its cost.

[0017] One approach to solve the problem involves the use of aphotoresist as a mask. However, it is well known that photoresists havelow etch resistance to certain plasma etching chemistries, particularlyfor the patterning of organic layers which may be employed asintermediate protecting layers or which are finding increasing use aslow-dielectric constant (“low-k”) dielectrics and low stopping power forions. Therefore, undesirably thick photoresist films are required topermit complete etching of the layer to be patterned prior to completeerosion of the masking layer or to prevent implantation of the areas ofthe substrate onto which they are applied. Another disadvantage is thation implanted photoresist can be exceedingly difficult to remove from awafer. Other solutions to the problem have been attempted, for example,by first applying a hard mask, then applying a photoresist layer atopthe hard mask followed by patterning before etching or ion implantationtake place. Combining some of the many steps disclosed in the-prior artmethods before plasma etching or ion implantation, or even eliminatingone or more of them, would help simplify these processes. Thus, a methodto eliminate steps in a plasma patterning or an ion implantation processwould be highly desirable.

[0018] The present processes for metal complex precursor deposition havebeen developed as less expensive methods of forming metal and metaloxide hard mask films. One embodiment of this process, photochemicalmetal organic deposition, involves the use of a metal organic for themetal complex precursor and a means for converting the metal organic tothe metal or metal oxide film, such as incident radiation or thermalenergy. Specifically, in this process, a precursor metal organic isapplied to a surface, for example, by dissolving it in a suitableorganic solvent to form a precursor solution, which is deposited onto asurface by any known means. The precursor is then at least partiallyconverted to a metal or metal oxide layer by a partial converting meansand/or converting means, such as by exposure to an energy source, e.g.,light, ion-beam bombardment, electron-beam bombardment, or thermal orheat treatment or annealing. As such, the present processes have utilityin, e.g., the semiconductor and packaging industries.

[0019] U.S. Pat. No. 5,534,312 to Hill et al. discloses aphotoresist-free method for making a patterned, metal-containingmaterial on a substrate which includes the steps of depositing anamorphous film of a metal complex on a surface of a substrate, placingthe film in a selected atmosphere, and exposing selected areas of thefilm to electromagnetic radiation, preferably ultraviolet light andoptionally through a mask, to cause the metal complex in the selectedareas to undergo a photochemical reaction. However, this reference doesnot envision use of a patterned, metal-containing material as a hardmask to protect underlying layers from a plasma etching environment.

[0020] U.S. Pat. No. 6,071,676 to Thomson et al. discloses that itsintegrated circuit manufacturing process causes degradation of anapplied compound where the compound is contacted by a radiant orparticle beam. In other words, the dimensions of the deposit caused bydegradation of the compound is proportional to the focal width of theirradiating beam. Nanoscale dimensions are disclosed to be achievable bythat process. Where the compound degrades to form a deposit of ametallic or other conductive substance, then the method may be used tomanufacture integrated circuits directly on a substrate. The deposit istaught to be, preferably, a metal or metal alloy, and the metals may begold, tin or chromium, or the deposit may be a conductive non-metal orsemi-metal, such as germanium. In a further aspect, there is provided amethod for manufacturing an integrated circuit comprising applying to asubstrate a compound which degrades under the effect of a radiant orparticle beam to produce a conductive, preferably metallic, deposit,applying to selected surface areas of the compound a radiant or particlebeam, and removing the degraded compound and the unaffected compoundfrom the substrate.

[0021] The processes of the present invention can provide a patternedhard mask, thus replacing both the oxide and photoresist layers used inconventional TSI and ion implantation methods and, for example,simplifying those methods by reducing the number of processing stepswhich must be performed. Another advantage of this invention is that thematerial which is produced has better etch resistance to plasma etchingchemistries. This confers still another advantage to the present processthat allows for the use of extremely thin films as the hard mask,increasing the ultimate resolution of the lithographic process andallowing the formation of smaller and finer features. A furtheradvantage of this invention is that the material which is produced hasbetter ion implant blocking and stopping power. Additionally, theprocess of the present invention is advantageous in that it facilitatesthe use of new materials for patterned layers, such as platinum,iridium, iridium oxide, ruthenium and ruthenium oxide, that are known inthe art to be difficult or impossible to etch by conventional processes.

[0022] The processes of the present invention are particularly useful inflexible electronics applications. In such applications, plastics aretypically used as a substrate or with other features. It is oftenpreferred to deposit a layer of some metal or metal oxide over suchplastics, for example, to act as a barrier layer from contaminants.Plastics, as well as other organic substrates, are finding wide use assubstrates in a number of emerging technologies, including, for example,organic light-emitting diodes (“OLEDs”). High-brightness OLEDs are ofgreat interest to the flat-panel display industry, among others. Theflat-panel display industry, among others, currently utilizesconventional processes to form thin metal and metal oxide films in theirproducts. However, conventional deposition methods can be harmful to theorganic matter, such as plastic substrates, due to the relatively highprocess temperature of conventional processes. In such applications, arelatively low temperature approach, such as the use of a photochemicalmetal organic deposition process (PMOD™) is preferable to avoid damagingthe organic material used in such applications because the PMOD™approach uses relatively low temperatures, such as ambient temperatures,in the deposition of metal and metal oxide films. Currently, sol-gelapproaches may be used to avoid the damage caused by the temperatures ofconventional deposition processes. However, sol-gel deposition processesresult in a high carbon residue that could impair the effectiveness ofsuch devices. Accordingly, a process to deposit metal and/or metal oxidelayers on organic substrates, is needed. The present PMOD™ process canbe used to deposit a metal or metal oxide layer on temperature sensitivematerials without suffering the high carbon residues of sol-gel and CVDprocesses. Accordingly, the PMOD™ approach is an effective solution forflexible applications and applications using organic (e.g., plastic)materials.

[0023] In addition, the use of OLED technology in flat panel displays,and other information display formats, is currently limited by the poorenvironmental stability of the devices, see U.S. Pat. No. 6,268,695 toAffinito. Because of this poor environmental stability, devices arecurrently fabricated on glass substrates and have glass covers laminatedover the top as an environmental barrier. Thus, even though the activeportions of the device are of a lightweight, thin film, flexible polymerconstruction, the finished part is heavy and rigid because of the glasssheets needed as environmental barriers to protect the device fromcontact by permeation of oxygen and/or water vapor. Accordingly, thePMOD™ approach is an effective solution for providing a lightweight andflexible alternative for such applications.

SUMMARY OF THE INVENTION

[0024] One embodiment of the present invention is a method of depositingmetal and metal oxide layers in applications where organic materials,such as plastics, are used. One such application, for example, is in themanufacture of OLED displays, in particular, flexible displays, usingthe low-cost PMOD™ methodology employing direct photoconversion ofmetal-organic precursor thin films. The PMOD™ methodology can be used inthat application, for example, to deposit barrier layers on plasticsubstrates at low temperatures. In addition to the ability to deposit avariety of material at a low temperature, the PMOD™ methodology permitsdirect photopatterning while resulting in low levels of residual carbonrelative to CVD and sol-gel processes. Metals, metal oxides andsilicates that are deposited are amorphous, which is an importantmaterial property for certain applications.

[0025] Another embodiment of the present invention is a method offorming a hard mask on a substrate comprising the steps of:

[0026] selecting at least one precursor material;

[0027] forming a layer comprising the precursor atop a substrate;

[0028] converting at least a portion of the precursor layer;

[0029] developing the precursor layer thereby forming a pattern in theprecursor layer; and

[0030] transferring the pattern to the substrate, whereby a photoresistis not used in forming the pattern.

[0031] The unconverted portion of the precursor layer can be developedaway an with a developer. Alternatively, the converted portion of theprecursor layer can be developed away an with a developer. The developercan be a liquid developer comprising at least one alcohol and at leastone ketone, wherein the total volume of all of the alcohols present isgreater than 50% of the sum of the volumes of all of the alcoholspresent plus the volumes of all of the ketones present in the liquiddeveloper. Preferably, at least one alcohol of the developer isisopropyl alcohol, the at least one ketone is methyl isobutyl ketone,and the ratio of isopropyl alcohol:methyl isobutyl ketone is fromgreater than about 1:1 by volume to less than about 40:1 by volume.

[0032] Another embodiment of the present invention is a method offorming a hard mask on a substrate, comprising the steps of:

[0033] selecting at least one precursor material;

[0034] optionally, forming a protective layer atop a substrate;

[0035] forming a layer comprising the unconverted precursor atop theprotective layer;

[0036] converting at least a portion of the unconverted precursor layer;

[0037] substantially removing at least a portion of the unconvertedprecursor layer to form a patterned hard mask.

[0038] Conversion can be accomplished with an energy source selectedfrom light, electron beam irradiation, ion beam irradiation, andmixtures thereof through a patterned mask comprising at least oneportion substantially transparent to the energy source. At least aportion of the unconverted precursor layer can be substantially removedby using a developer.

[0039] An alternate embodiment of the present invention is a method offorming an etched pattern in a substrate, comprising the steps of:

[0040] selecting at least one precursor material;

[0041] forming a layer comprising the unconverted precursor atop asubstrate;

[0042] converting at least a portion of the unconverted precursor layer;

[0043] substantially removing at least a portion of the unconvertedprecursor layer, thereby forming a patterned hard mask; and

[0044] forming at least one patterned region in the substrate by etchingat least a portion of the substrate substantially uncovered by the hardmask.

[0045] Another embodiment of the present invention is a method offorming an implanted region in a substrate, comprising the steps of:

[0046] selecting at least one precursor material;

[0047] optionally, forming a protective layer atop the substrate;

[0048] forming a layer comprising the at least one unconverted precursormaterial atop the protective layer;

[0049] converting at least a portion of the precursor layer;

[0050] substantially removing at least a portion of the unconvertedprecursor layer by using a developer to form a patterned hard mask; and

[0051] forming at least one implanted region in the substrate byimplanting ions in at least a portion of the substrate substantiallyuncovered by the hard mask.

[0052] Conversion can be accomplished with an energy source selectedfrom light, electron beam irradiation, ion beam irradiation, andmixtures thereof. Ions can be implanted by exposing the uncoveredsubstrate to an ion beam.

[0053] A further embodiment of the present invention is a method offorming a dual damascene architecture in a dielectric layer, comprisingthe steps of:

[0054] selecting at least one precursor material;

[0055] forming the dielectric layer with a characteristic thickness atopa substrate;

[0056] forming a layer comprising a first unconverted precursor atop thedielectric layer;

[0057] forming a converted portion of the first precursor layer by usinga first converting means on at least a portion of the unconverted firstprecursor layer;

[0058] substantially removing at least a portion of the firstunconverted precursor layer to expose at least a portion of thedielectric layer by using a first removing means to form a first patternuncovered by the converted first precursor layer, thereby forming afirst hard mask;

[0059] forming a spin planarization layer atop the exposed portion ofthe dielectric layer and atop the converted first precursor layer;

[0060] forming a layer comprising a second unconverted precursor atopthe spin planarization layer;

[0061] forming a converted portion of the second precursor layer byusing a second converting means on at least a portion of the unconvertedsecond precursor layer;

[0062] substantially removing at least a portion of the secondunconverted precursor layer to expose at least a portion of the spinplanarization layer by using a second removing means to form a secondpattern uncovered by the converted second precursor layer, therebyforming a second hard mask;

[0063] forming at least one second patterned region in the dielectriclayer by using a first etching means on at least a portion of thedielectric layer and its overlying spin planarization layersubstantially uncovered by the second hard mask such that less than thethickness of the dielectric layer in depth is removed by the firstetching means;

[0064] substantially removing the remaining converted second precursorlayer and spin planarization layer by using a third removing means,thereby exposing the converted first precursor layer;

[0065] forming at least one first patterned region in the dielectriclayer by using a second etching means on at least a portion of thedielectric layer substantially uncovered by the first hard mask suchthat less than the thickness in depth of the dielectric layer is removedby the second etching means in the first patterned region and thatsubstantially the entire thickness of the dielectric layer in depth isremoved by the second etching means in the second patterned region,thereby uncovering at least a portion of the substrate; and

[0066] optionally, substantially removing the remaining converted firstprecursor layer by using a fourth removing means.

[0067] Preferably, the dielectric layer is a low-dielectric constantdielectric material. Preferably, at least one of the first and secondetching means is an anisotropic plasma comprising oxygen.

[0068] In each embodiment of the invention, a preferred precursormaterial is a metal complex comprising at least one ligand selected fromthe group consisting of acac, carboxylato, alkoxy, azide, carbonyl,nitrato, amine, halide, nitro, and mixtures thereof and at least onemetal selected from the group consisting of Li, Al, Si, Ti, V, Cr, Mn,Fe, Ni, Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Ba, La,Pr, Sm, Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As, Ce, Mg,and mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0069]FIG. 1 is a process flow diagram which identifies processvariables by process step.

[0070]FIG. 2 illustrates the basic sequence of steps in an embodiment ofthe process of the present invention.

[0071]FIG. 3 illustrates a prior art method of fabrication and use of ahard mask used in semiconductor interconnect.

[0072]FIG. 4 illustrates a method of fabrication and use of a hard maskaccording to the present invention.

[0073]FIG. 5 illustrates a prior art method of patterning by TSI.

[0074]FIG. 6 illustrates a method of fabrication and use of a TSI layeraccording to the present invention.

[0075]FIG. 7 illustrates a prior art method of effecting a liftoffprocess.

[0076]FIG. 8 illustrates a method of effecting a liftoff processaccording to the present invention.

[0077]FIG. 9 illustrates an alternate method of effecting a liftoffprocess according to the present invention.

[0078]FIG. 10 illustrates a prior art method for dual damascene processintegration.

[0079]FIG. 11 illustrates a method for dual damascene processintegration according to the present invention comprising fewer stepsthan FIG. 10.

[0080]FIG. 12 illustrates a prior art method of fabricating an ionimplantation hard mask and implanting ions therewith.

[0081]FIG. 13 illustrates a process of fabricating an ion implantationhard mask according to an embodiment of the present invention andimplanting ions therewith.

[0082]FIG. 14 shows the different refractive index properties exhibitedby ZrO₂ films formed from two different precursors.

[0083]FIG. 15 shows the refractive indexes of various ZrO₂ films formedby thermal and photochemical conversion.

[0084]FIG. 16 depicts streaks caused by the use of a particular solventafter applying a precursor solution to a substrate.

[0085]FIG. 17 shows a thermal contrast curve for BST.

[0086]FIG. 18 shows a photochemical contrast curve for BST.

[0087]FIG. 19 shows a combined thermal/photochemical contrast curve forBST.

[0088]FIG. 20 is a plot of thickness versus etching time for hard bakedNovolac.

[0089]FIG. 21 is an cross section of an organic light emitting diode.

[0090]FIG. 22 is a diagram of an organic light emitting diode.

DETAILED DESCRIPTION OF THE INVENTION

[0091] The present process allows for advantages unavailable with otherfilm deposition and formation methods. As a result, it presents the userwith a greater ability to control and manipulate the characteristics ofthe resulting film to suit the desired application. Therefore, thepresent process is useful in a broad spectrum of applications.

[0092] This invention provides a process for making a patterned film ofdesired materials. It is important to recognize that amorphous films aredistinct from polycrystalline and crystalline films; further, whileamorphous films are distinct from more ordered films, in addition,different amorphous films formed by different film-forming methods aredifferent from one another. Further still, the different properties ofdifferent amorphous films formed by different methods can be controlledand engender specific chemical, physical and mechanical properties thatare useful in particular applications, for example, as a layer(s) in asemiconductor device and/or in their fabrication. The hard masks formedby the present processes which comprise a step of at least partiallyconverting such amorphous films are preferably patterned and aretherefore useful for transferring a pattern to a substrate. Hard masksinclude but are not limited to implantation masks, etch masks, andpattern transfer layers or masks, e.g., liftoff masks.

[0093] One advantage of an embodiment of the present process is that ityields a patterned electronic material without using a conventionalpatterning material, i.e., a photoresist, in forming the pattern.Another advantage of the present process is that the amorphous films ofprecursor material which may be formed may optionally be directlypatterned on a substrate, without the use of intermediate patterningmaterials. As a result of an understanding of process variables,important and unique properties are attainable though this depositionprocess that are not by the use of other film deposition and formationmethods. FIG. 1 provides an overview of the present process by a processflow diagram showing exemplary steps that may be followed to obtain afilm of the desired material with optimized properties for a particularapplication. Many of these steps are fully optional, based on theultimate application of the film. The present invention is also notlimited to these steps and may include other steps, based on theultimate application of the film. One skilled in the art will know whichsteps should be included or excluded to achieve the desired result forthe particular application.

[0094] At each step, variables exist that may be manipulated to affectthe resulting film. For example, at step 1 of FIG. 1, the variables mayinclude the composition of the precursor material, the solvent used inthe precursor material, whether a solvent is used in the precursormaterial, the additives that may be used with the precursor material,and/or rate enhancers that may be included with the precursor material.

[0095] At step 2 of FIG. 1, the variables may include cleaning thesubstrate, the deposition of a barrier layer, the deposition of anadhesion promoter, and/or the use of a reactive layer.

[0096] At step 3 of FIG. 1, the variables may include the method ofapplying the precursor film, the atmosphere in which the precursor isapplied, and/or the temperature of the deposition.

[0097] At step 4 of FIG. 1, the variables may include a thermaltreatment, treatment with an electron beam, treatment with an ion beam,treatment using microwaves, and/or the use of a particular atmosphere.

[0098] At step 5 of FIG. 1, the variables may include whether the filmis blanket exposed or patterned or a blend of each and/or the use of aparticular atmosphere.

[0099] At step 6 of FIG. 1, the variables may include a thermal anneal,treatment using microwaves, treatment with an electron beam, treatmentwith an ion beam, plating, and/or the use of a particular atmosphere.

[0100] At step 7 of FIG. 1, the variables may include patterning witheither wet or dry techniques.

[0101] At step 8 of FIG. 1, the variables may include annealing and/orthe use of a particular atmosphere. Also, at this step, any amorphousfilm formed may be converted to polycrystalline or crystalline films,e.g., by the application of elevated temperatures or various othernucleation processes, such as photo-induced nucleation, and that forsome applications this may be a desirable process step.

[0102] These variables are intended as examples and are not to beconsidered exhaustive lists of the variables that may be manipulated toaffect the properties of the resulting film. More specific aspects andembodiments of the present invention are described in detail below.

[0103] Where a patterned film is desired, the process described here mayproceed photochemically, without the use of an intermediate patterningmaterial, e.g., a photoresist, and may be undertaken under ambientconditions, or may be undertaken under other conditions such as eitheran air or other composition atmosphere and/or under a variety ofpressures, e.g., ambient, higher or lower than ambient, and may be usedin conjunction with, a variety of other processing steps to yield uniquematerials, layers and structures.

[0104] Where the process is performed photolytically, the processproceeds at substantially ambient temperatures while other prior artmethods require the use of elevated temperatures to effect patterntransfer, often greater than 100° C. This limitation confers severeprocessing constraints from a manufacturing standpoint and limits thechoice of materials used in the assembly of devices associated with theapplications of the method.

[0105] The process of the present invention usually proceedssatisfactorily under substantially ambient pressure. In contrast, manyof the prior art deposition methods, in addition to having theaforementioned limitations, must be undertaken under conditions of highvacuum, invoking the necessity for expensive and complicated equipmentthat is difficult to run and maintain.

[0106] The processes of the present invention facilitate the formationof a thin layer on a substrate from a precursor material. The precursorcomprises molecules specifically designed for their ability to coat thesubstrate in a uniform manner, resulting in films of high opticalquality, and, in the case of the present process, for photosensitivity.The identity of the precursor molecule is a significant variable—a widevariety of metal complexes of the formula M_(a)L_(b) comprising at leastone metal (“M”), i.e., a is an integer which is at least 1, and at leastone suitable ligand (“L”) or ligands, i.e., b is an integer which is atleast 1, are envisioned by this invention.

[0107] If a plurality of metals are used, all of the metal atoms may beidentical, all may be different atoms and/or have different valences,e.g., Ba Na or Fe(II) Fe(III), or some may be identical while others maybe different atoms and/or have different valences, e.g., Ba₂ Fe(II)Fe(III). In any case, metal M may be an alkali or alkaline earth, forexample Ba or Li, a transition metal, for example Cr or Ni, a main groupmetal, for example Al or Sn, or an actinide, for example U or Th.Preferably, each metal is independently selected from Li, Al, Si, Ti, V,Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn,Ba, La, Pr, Sm, Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As,Ce, and Mg.

[0108] If a plurality of ligands are used, all of the ligands may beidentical, all may be different, or some may be identical while othersmay be different. In any case, ligand L is chosen so that asubstantially unconverted precursor complex can be formed and has theproperties that:

[0109] 1) it can be deposited in an amorphous film on a substrate,

[0110] 2) the amorphous film is stable or, at least, metastable,

[0111] 3) upon absorbing energy, e.g., a photon of the required energy,the film can be transformed into a different metal-containing materialthrough a chemical reaction, and

[0112] 4) any byproducts of the energy-induced chemical reaction shouldbe removable, i.e., should be sufficiently volatile so as to beremovable from the film.

[0113] To achieve the first two of these results, the complex shouldhave a low polarity and low intermolecular forces. As organic groupsusually have low intermolecular forces, ligands having organic groups attheir outer peripheries tend to be satisfactory with respect to thefirst two requirements. If the energy absorbed is light, the chemicalreaction of step (3) is known as a photo-induced reaction.

[0114] The deposited film of substantially unconverted precursor isamorphous or at least substantially amorphous. Therefore, to make themetal complex resistant to crystallization, ligand(s) L preferably aresuch that the complex is asymmetric. The complex may be made asymmetricby using a ligand which itself has two or more stereoisomeric forms. Forexample, if L is racemic 2-ethylhexanoate, the resulting metal complexis asymmetric because the complex has several different stereoisomericforms. The size and shapes of organic portions of the ligands may beselected to optimize film stability and to adjust the thickness of filmthat will be deposited by the selected film deposition process.

[0115] The stability of an amorphous film with respect tocrystallization may also be enhanced by making the film of a complexwhich has several different ligands attached to each metal atom. Suchmetal complexes have several isomeric forms. For example, the reactionof CH₃HNCH₂CH₂NHCH₃ with a mixture of a nickel(II) salt and KNCS leadsto the production of a mixture of isomers. The chemical properties ofthe different isomers are known not to differ significantly, however,the presence of several isomers in the film impairs crystallization ofthe complex in the film.

[0116] The complex must also be stable, or at least metastable, in thesense that it will not rapidly and spontaneously decompose under processconditions. The stability of complexes of a given metal may depend, forexample, upon the oxidation state of the metal in the complex. Forinstance, Ni(0) complexes are known to be unstable in air while Ni(II)complexes are air-stable. Consequently, a process for depositing Nibased films which includes processing steps in an air atmosphere shouldinclude a Ni(II) complex in preference to a Ni(0) complex.

[0117] Partial conversion and conversion result from a chemical reactionwithin the film which changes the partially converted or convertedregions into a desired converted material. Ideally, at least one ligandshould be reactive and be attached to the complex by a bond which iscleaved when the complex is raised to an excited state by the influenceof the partial converting means and/or the converting means. Preferablythe reactive group is severed from the complex in a photochemicalreaction initiated by light, more preferably, by ultraviolet light, asthe partial converting means and/or the converting means. To make suchphotochemical step(s) in the process efficient, it is highly preferablethat the intermediate product produced when the reactive group issevered be unstable and spontaneously convert to the desired newmaterial and volatile byproduct(s).

[0118] There are several mechanisms by which a suitable photochemicalreaction may occur. Some examples of suitable reaction mechanisms whichmay be operable, individually or in combination, according to theinvention are as follows: (a) absorption of a photon may place thecomplex in a ligand to metal charge transfer excited state in which ametal-to-ligand bond in the metal complex is unstable, the bond breaksand the remaining parts of the complex spontaneously decompose, (b)absorption of a photon may place the complex in a metal-to-ligand chargetransfer excited state in which a metal-to-ligand bond in the complex isunstable, the bond breaks and the remaining parts of the complexspontaneously decompose, (c) absorption of a photon may place thecomplex in a d-d excited state in which a metal-to-ligand bond in thecomplex is unstable, the bond breaks and the remaining parts of thecomplex spontaneously decompose, (d) absorption of a photon may placethe complex in an intramolecular charge transfer excited state in whicha metal-to-ligand bond in the complex is unstable, the bond breaks andthe remaining parts of the complex spontaneously decompose, (e)absorption of a photon may place at least one ligand of the complex in alocalized ligand excited state, a bond between the excited ligand andthe complex is unstable, the bond breaks and the remaining parts of thecomplex spontaneously decompose, (f) absorption of a photon may placethe complex in an intramolecular charge transfer excited state such thatat least one ligand of the complex is unstable and decomposes, then theremaining parts of the complex are unstable and spontaneously decompose,(g) absorption of a photon may place at least one ligand of the complexin a localized ligand excited state wherein the excited ligand isunstable and decomposes, then the remaining parts of the complex areunstable and spontaneously decompose, and (h) absorption of a photon mayplace the complex in a metal-to-ligand charge transfer excited state inwhich at least one ligand of the complex is unstable and decomposes,then the remaining parts of the complex are unstable and spontaneouslydecompose. In its broad aspects, however, this invention is not to beconstrued to be limited to these reaction mechanisms.

[0119] Exemplary metal complexes, and their metal and ligand components,are described in U.S. Pat. No. 5,534,312 which is incorporated herein byreference in its entirety. Preferred metal complex precursors includeligands which meet the above criteria. More preferably, the ligands areselected from the group consisting of acetylacetonate (also known as“acac” or 2,4-pentanedione) and its anions,

[0120] substituted acetylacetonate, i.e.,

[0121] and their anions, acetonylacetone (also known as 2,5-hexanedione)and its anions

[0122] substituted acetonylacetone, i.e.,

[0123] and its anions,

[0124] dialkyldithiocarbamates, i.e.,

[0125] and its anions,

[0126] carboxylic acids, i.e,

[0127] such as hexanoic acid where R=CH₃(CH₂)₄,

[0128] carboxylates, i.e.,

[0129] such as hexanoic acid where R=CH₃(CH₂)₄,

[0130] pyridine and/or substituted pyridines, i.e.,

[0131] azide, i.e., N₃ ⁻, amines, e.g., RNH₂, diamines, e.g., H₂RNH₂

[0132] arsines, i.e.,

[0133] diarsines, i.e.,

[0134] phosphines, i.e.,

[0135] diphosphines, i.e.,

[0136] arenes, i.e.,

[0137] hydroxy, i.e., OH⁻, alkoxy ligands, e.g., RO⁻, ligands such as(C₂H₅)₂NCH₂CH₂O—, alkyl ligands, e.g., R^(—), aryl ligands, and mixturesthereof, where each R, R′, R″, R′″, and R″″ is independently selectedfrom organic groups and, preferably, is independently selected fromalkyl, alkenyl, aralkyl and aralkenyl groups.

[0138] As used herein, the term “alkyl” refers to a straight or branchedhydrocarbon chain. As used herein, the phrase straight chain or branchedchain hydrocarbon chain means any substituted or unsubstituted acycliccarbon-containing compounds, including alkanes, alkenes and alkynes.Examples of alkyl groups include lower alkyl, for example, methyl,ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl oriso-hexyl; upper alkyl, for example, n-heptyl, -octyl, iso-octyl, nonyl,decyl, and the like; lower alkylene, for example, ethylene, propylene,propylyne, butylene, butadiene, pentene, n-hexene or iso-hexene; andupper alkylene, for example, n-heptene, n-octene, iso-octene, nonene,decene and the like. The ordinary skilled artisan is familiar withnumerous straight, i.e., linear, and branched alkyl groups, which arewithin the scope of the present invention. In addition, such alkylgroups may also contain various substituents in which one or morehydrogen atoms is replaced by a functional group or an in-chainfunctional group.

[0139] As used herein, the term “alkenyl” refers to a straight orbranched hydrocarbon chain where at least one of the carbon-carbonlinkages is a carbon-carbon double bond. As used herein, the term“aralkyl” refers to an alkyl group which is terminally substituted withat least one aryl group, e.g., benzyl. As used herein, the term“aralkenyl” refers to an alkenyl group which is terminally substitutedwith at least one aryl group. As used herein, the term “aryl” refers toa hydrocarbon ring bearing a system of conjugated double bonds, oftencomprising at least six π (pi) electrons. Examples of aryl groupsinclude, but are not limited to, phenyl, naphthyl, anisyl, toluyl,xylenyl and the like.

[0140] The term “functional group” in the context of the presentinvention broadly refers to a moiety possessing in-chain, pendant and/orterminal functionality, as understood by those persons of ordinary skillin the relevant art. As examples of in-chain functional groups may bementioned ethers, esters, amides, urethanes and their thio-derivatives,i.e., where at least one oxygen atom is replaced by a sulfur atom. Asexamples of pendant and/or terminal functional groups may be mentionedhalogens, such as fluorine and chlorine, and hydrogen-containing groupssuch as hydroxyl, amino, carboxyl, thio and amido, isocyanato, cyano,epoxy, and ethylenically unsaturated groups such as allyl, acryloyl andmethacryloyl, and maleate and maleimido.

[0141] To enhance the desired photochemical characteristics, includingthe tendency of the products of the photochemical reaction tospontaneously thermally decompose, ligands comprising and/or selectedfrom one or more of the following groups may be used alone or incombination with the above-ligands: oxo, i.e., O₂ ⁻

[0142] oxalato, i.e.,

[0143] halide, hydrogen, hydride, i.e., H⁻, dihydride, i.e., H₂,hydroxy, cyano, i.e., CN⁻, carbonyl, nitro, i.e., NO₂, nitrito, i.e.,NO₂ ⁻, nitrate, i.e, NO₃, nitrato, i.e., NO3⁻, nitrosyl, i.e., NO,ethylene, acetylenes, i.e., RR′ thiocyanato, i.e., SCN—,isothiocyanato, i.e., NCS⁻, aquo, i.e., H₂O, azides, carbonato, i.e.,CO₃ ⁻², amine, and thiocarbonyl, where each R and R′ is independentlyselected from organic groups and, preferably, is independently selectedfrom alkyl, alkenyl, aralkyl and aralkenyl groups. Even more preferably,each ligand is independently selected from acac, carboxylates, alkoxy,oxalato, azide, carbonyl, nitro, nitrato, amine, halogen and theiranions.

[0144] Preferably, the metal complex precursor is selected from thosecomprising at least one ligand selected from the group consisting ofacac, carboxylato, alkoxy, azide, carbonyl, nitrato, amine, halide,nitro, and mixtures thereof and at least one metal selected from thegroup consisting of Li, Al, Si, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr,Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Ba, La, Pr, Sm, Eu, Hf, Ta, W,Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As, Ce, Mg, and mixtures thereof.

[0145] The precursor may be applied to the substrate directly.Alternatively and preferably, the precursor is dissolved in a solvent orsolvents to form a precursor solution. This facilitates its applicationto the substrate by a variety of means well known to those of ordinaryskill in the art, such as by spin or spray application of the solutionto the substrate. The solvent may be chosen based on several criteria,individually or in combination, including the ability of the solvent todissolve the precursor, the inertness of the solvent relative to theprecursor, the viscosity of the solvent, the solubility of oxygen orother ambient or other gases in the solvent, the UV, visible, and/orinfra-red absorption spectra of the solvent, the absorptioncross-section of the solvent with respect to electron and/or ion beams,the volatility of the solvent, the ability of the solvent to diffusethrough a subsequently formed film, the purity of the solvent withrespect to the presence of different solvent isomers, the purity of thesolvent with respect to the presence of metal ions, the thermalstability of the solvent, the ability of the solvent to influence defector nucleation sites in a subsequently formed film, and environmentalconsiderations concerning the solvent. Exemplary solvents include thealkanes, such as hexanes, the ketones, such as methyl isobutyl ketone(“MIBK”) and methyl ethyl ketone (“MEK”), and propylene glycolmonomethyl ether acetate (“PGMEA”).

[0146] The concentration of the precursor in the solution may be variedover a wide range and may be chosen by one of ordinary skill in the artwith, at most, minimal routine experimentation, such that the propertiesof the precursor film, including its thickness and/or sensitivity toirradiation by light or particle beams, are appropriate for the desiredapplication.

[0147] However, the choice of precursor may have a significant influenceon the properties of the desired film which is not readily predictableby one skilled in the art. For example, two precursors ML and ML′, eachconsisting of metal M and one of two different ligand sets L or L′,might be expected to form films of the desired material which areidentical because, e.g., the portions of the ligands which differ fromeach other would be removed during conversion of the precursor into ahard mask. In fact, the supposedly identical film products of these twosimilar reactants may differ significantly in their properties. Examplesof properties which may be affected in this process include thedielectric constant and the presence/absence of any secondary ortertiary structure in the film. Possible reasons for this difference mayrelate to the rate of formation of the amorphous material and theability of the photo-ejected ligand to remove energy from thephoto-produced film of desired material. The presence of ligandfragments during an exposure process may also affect the film formingprocess, influencing such phenomena as diffusion properties of the film,nucleation, and crystal growth.

[0148] Further, the choice of the precursor in film formation andphotochemical exposure can substantially influence further reactivity ofthe film of the desired material with, for example, gaseous constituentsof the atmosphere in which the desired film is formed. This couldinfluence, for example, the rate of oxidation of the deposited filmwhere either a high or low rate could be an advantage depending upon thedesired product. Additionally, it is recognized that the effect of theprecursor upon the healing ability of the film, i.e., its ability tominimize crazing, and the shrinkage or densification of the film may besubstantially influenced by the choice of precursors that wouldotherwise be seen to yield identical results by one skilled in the art.

[0149] Chemical additives are optionally present with the precursor orin the precursor solution. These may be present for any or several ofthe following reasons: to control the photosensitivity of a subsequentlydeposited precursor or film, to aid in the ability to deposit uniform,defect-free films onto a substrate, to modify the viscosity of thesolution, to enhance the rate of film formation, to aid in preventingfilm cracking during subsequent exposure of the deposited film, tomodify other bulk properties of the solution, and to modify in importantways the properties of the film of the desired material. The additivesare chosen on these criteria in addition to those criteria employed whenchoosing a suitable solvent. It is preferable that the precursor or theprecursor solution be substantially free of particulate contamination soas to enhance its film-forming properties.

[0150] The nature of the substrate to which the precursor is applied isnot critical for the process although it may effect the method ofdeposition of the precursor film and the solvent for the deposition, ifone is used. Substrates may include but are not limited to simple salts,such as CaF₂, semiconductor surfaces, including silicon, compoundsemiconductors, including silicon germanium and III-V and II-VIsemiconductors, printed and/or laminated circuit board substrates,metals, ceramics, and glasses. Silicon wafers, ceramic substrates andprinted circuit boards have been used extensively. Prior to its use inthe present process, the substrate may have been coated with single ormultiple layers, such as dielectric layers, photoresist, polyimide,metal oxides, thermal oxides, conductive materials, insulatingmaterials, ferroelectric materials or other materials used in theconstruction of electronic devices. In cases where patterning is to beeffected by an oxygen plasma, and the precursor material is to beemployed as a TSI agent, the underlying layer is likely to be organic innature, including but not limited to Novolac resin, poly(methylmethacrylate) (“PMMA”), poly(methyl glutarimide) (“PMGI”), polyimide,and poly(p-hydroxystyrene) (“PHOST”).

[0151] To the extent that metal atoms in the hard mask, once formed,might be “bumped” into the underlying substrate during a subsequentstep, this can be overcome by careful selection of precursor formulationconditions and/or thickness. Alternatively, an optional protective layercan be used between the substrate and the precursor layer which remainsto protect the substrate after the hard mask forming process iscompleted. Optionally, the substrate may be coated with at least oneprotective layer before the precursor or precursor solution is applied.The protective layer may be applied to the substrate by a variety ofmeans well known to those of ordinary skill in the art. Protectivelayers are particularly desirable when the process includes an ionimplantation step.

[0152] The preparation of the substrate prior to deposition of theprecursor film can have a significant impact on the ultimate nature ofthe desired hard mask. Thus, certain surface preparations may bedesirable or, conversely, may need to be avoided depending upon theparticular hard mask used. Substrate preparations may include a simplecleaning process to remove unwanted species from the substrate surface,a prior patterning step, the deposition of a barrier material, thedeposition of an adhesion promoting material, or the deposition of areactive material designed to induce chemical change in the film ofdeposited material, e.g., a coupling agent.

[0153] The method of application of the precursor or the precursorsolution may be chosen depending on the substrate and the intendedapplication. Some examples of useful coating methods well known to thoseof ordinary skill in the art include spin, spray, dip and rollercoating, stamping, meniscus, and various inking approaches, e.g.,inkjet-type approaches. Variables in the coating process may be chosenin order to control the thickness and uniformity of the deposited film,to minimize edge effects and the formation of voids or pinholes in thefilm, and to ensure that no more than the required volume of precursoror precursor solution is consumed during the coating process. Optimizedapplication of the precursor film may desirably yield very smooth films.

[0154] The deposited film may, optionally, be subjected to a baking orvacuum step where any residual solvent present in the deposited film maybe driven off. If a baking step is employed, it is, of course, importantto keep the temperature of this step below the temperature at which theprecursor molecules decompose thermolytically. The process of theinvention allows for blanket thermal or heat treatment or annealing ofthe precursor cast film so as to convert it thermolytically into ablanket uniform coating of the desired material, or to a film thatrequires a lower partial converting means and/or converting means dosefor patterning than would have been possible without the thermaltreatment. The deposited film may optionally be subjected to othertreatments at this stage of the process, including but not limited toblanket photochemical or electron beam exposure and microwave treatment.

[0155] It is recognized that a bake step at this stage of the processmay contribute to ejecting solvent from the precursor film and alsoinitiate a thermal decomposition process. Both of these mechanisms mayaid in the overall efficiency of the process resulting in, for example,a lower dose requirement during a subsequent partial converting and/orconverting step. It is further recognized that during such a bake step,a new material, different from either the deposited film or the film ofthe desired material, may be formed. The effect of this could altersignificantly subsequent properties of the desired material, includingdielectric constant, nucleation, speciation, and crystallizationbehavior in ways that are not readily predicted by one skilled in theart. For example, a two component system in which one material isactivated in the pre-bake step while the other component(s) is selectedto be activated in either a photochemical or higher energy thermalprocess step may be preferred in certain applications. This deposition,from a mixture of precursors, would permit the efficient design of asystem to take advantage of the different chemical properties ofmaterials formed from the bake and subsequent partial converting and/orconverting step(s).

[0156] The deposited film is next subjected to a partial convertingmeans and/or converting means, i.e., a source of energy, such that theprecursor is at least partially converted. The entire film, or selectedregions of the deposited precursor film, may be exposed to a source ofenergy. The energy source may be, e.g., a light source of a specificwavelength, a coherent light source of a specific wavelength orwavelengths, a broadband light source, an electron beam (“e-beam”)source, or an ion beam source. Light in the wavelength range of fromabout 150 to about 600 nm is suitably used. Preferably, the wavelengthof the light is from about 157 to about 436 nm.

[0157] In certain embodiments of the invention, the energy source is alight source directed through an optical mask used to define an image onthe surface. The mask consists of substantially transparent andsubstantially opaque or light absorbing regions. The mask may alsoinclude an optical enhancing feature such as a phase shift technology.However, the energy source need not be directed through a mask. Forexample, if it is not necessary to pattern the material, a flood orblanket energy exposure may be used, such as is provided by thermalenergy or a wide beam of light.

[0158] The atmosphere and pressure, both total and partial, under whichthe deposited film is at least partially converted may be importantprocess variables. Normally, it is convenient and economical for theatmosphere to be air but it may be preferable to change the compositionof the atmosphere present during at least partial conversion. One reasonfor this is to increase the transmission of the exposing light, if shortwavelength light is used, because such light may be attenuated by air.Thus, by varying the intensity of the light, e.g., increasing it, it ispossible to initiate thermal reaction within the films to generateproduct films. It may also be desirable to change the composition of theatmosphere to alter the composition or properties of the product film.For example, the exposure of a copper complex results in the formationof a copper oxide in air or oxygen atmospheres. By virtually eliminatingoxygen from the atmosphere, a film comprising primarily reduced copperspecies may be formed. For example, a partial conversion or conversionstep is preferably performed in the presence of oxygen if the convertedprecursor is to be a dielectric film or in the presence of a reducinggas, such as hydrogen, if the converted precursor is to be a metallicfilm. Additionally, the amount of water in the film may be changed bychanging the humidity of the atmosphere.

[0159] The use of a partial conversion step, or different conversionsteps in sequence, also known as “substrate pretreatment”, may beadvantageous from a process flow standpoint, for example, in order tominimize the time during which a precursor atop a substrate needs to beexposed in an expensive piece of equipment, such as a stepper.

[0160] Following at least partial conversion of the deposited precursor,the precursor film may, optionally, be treated by any of a variety ofmethods well known to the art prior to removing at least a portion ofthe unconverted precursor layer. These methods include but are notlimited to annealing treatments, such as thermal, laser or plasmaannealing steps, exposure to a specific atmosphere, e.g., oxidizing orreducing, ion implantation, microwave treatment and electron beamtreatment. If the at least partial converted area(s) may serve aselectroless plating nucleation sites relative to the unconverted area(s)of the precursor, then an optional plating step may be used at thisstage.

[0161] Unexposed regions of the deposited film, or a portion thereof,may then be removed by the application of a removing (or developing)means. For example, a developing means may comprise a developercomposition that may be applied as a liquid or a solution in a puddledevelopment or immersion wet development process. Alternately, a drydevelopment process analogous to dry patterning steps conventionallyemployed by the semiconductor industry may be employed as a developingmeans. Preferred removal means include spray development, puddledevelopment, and immersion wet development.

[0162] The developer should be formulated and/or used under conditionssuch that a solubility difference exists between exposed and unexposedregions of the film. This solubility difference is used to removepreferentially select regions of the film such that certain chosenregions of the film are substantially removed by the developer whileregions desired to remain on the substrate are left substantiallyintact. Considerable experimentation may be required to optimize theformulation of the developer. For example, in a process in which regionsthat have been exposed to incident energy are desired to remain on thesubstrate, use of the casting solvent to develop the film after exposureto incident radiation is too aggressive. A dilute solution of thecasting solvent in another liquid in which (a) the casting solvent ismiscible, (b) unexposed regions of the film are sparingly (but notnecessarily completely) soluble, and (c) exposed regions of the film aresubstantially insoluble, provides for an improved development process.

[0163] For instance, in one preferred embodiment of the invention anamorphous film may be cast from a ketone solution. Use of the ketonealone as a developer, or a ketone-rich mixture of alcohol and theketone, i.e., a mixture with greater than 50 vol.% ketone, results in adevelopment process that is less effective than when the alcohol is themajority component. For instance, 10:1 (vol/vol) IPA:MIBK solution is amore effective developer for Ba_(x)Sr_(y)Ti_(z)O₃ (“BST”) than MIBKalone or 1:1 (vol/vol) IPA:MIBK, where “IPA” signifies isopropylalcohol. The 10:1 mixture, in turn, is less effective than 20:1IPA:MIBK. However, both of the 10:1 and 20:1 solutions are moreeffective than a solution of 40:1 (vol/vol) IPA:MIBK. Furthermore, therelative effectiveness of these solutions depends heavily on otherprocesses employed in the formation of the patterned film including, forexample, the type and energy of incident radiation and the temperatureof the substrate during coating and patterning. Thus, the determinationof an appropriate developer formulation for the present inventionrequires experimentation and is not obvious to one of ordinary skill inthe art. Liquid and/or solution-based developers may be physicallyapplied in a fashion analogous to development methods employed withphotoresist-based processes, for example, those discussed above.

[0164] After development, the at least partially converted precursormay, optionally, be treated by any of a variety of methods well known tothe art prior to its being subjected to a converting means. Thesemethods include but are not limited to annealing treatments, such asthermal, laser or plasma annealing. The temperature and time of suchannealing are important variables. The annealing step may also beinfluenced by prior surface treatments, for example, oxygen plasma,laser or a rapid thermal annealing (“RTA”) process. It is possible toselect appropriate conditions such that the annealed at least partiallyconverted precursor retains its amorphous nature while at least one ofits physical or electrical properties is desirably altered.Alternatively, annealing conditions that cause the film to convert toits crystalline state, e.g., a high temperature, may be desirabledepending on the application for which the film is to be used. Forexample, appropriate thermal treatment at this stage may be employed toinduce the formation of highly oriented crystalline films from theamorphous or at least substantially amorphous at least partiallyconverted precursor. In this manner, the properties of the amorphousfilm may be finely tuned or its physical properties may even be variedover a wide range—from the completely amorphous phase at one extreme tosemi-crystalline intermediate phases to a single oriented crystallinephase at the other extreme. Such thermal treatment will usually act tofurther convert the precursor.

[0165] If the precursor has yet to be substantially fully converted, theprecursor film is next optionally but typically subjected to aconverting means such that the precursor is substantially fullyconverted. The entire film or selected regions of the precursor film maybe exposed to a source of energy. The converting means can be an energysource that may be the same as or different from any partial convertingmeans previously employed. For example, the converting means may be alight source of a specific wavelength, a coherent light source of aspecific wavelength, a broadband light source, an electron beam source,and/or an ion beam source. In certain embodiments of the invention, theenergy source, or at least a portion of the energy source, is a lightsource directed through an optical mask used to define an image on thesurface, as discussed above. However, the energy source need not bedirected through a mask. For example, it may not be necessary to patternthe material during the conversion step, e.g., because the precursor mayalready be patterned, therefore, a flood or blanket exposure may be usedas the converting means. Preferred converting means include light,electron beam, ion beam, and thermal treatment. As discussed above forpartial conversion and as is also applicable here, the atmosphericconditions under which the deposited film is converted, such asatmosphere composition, pressure, both total and partial, and humidity,may be important process variables. During conversion, these variablesmay be the same as or different from their settings used in anypreceding partial conversion step.

[0166] It is, of course, to be understood that, as a preferred thinfilm, e.g., hard mask, may be formed by substantially fully convertingat least one portion of the partially converted precursor layer, theterms “substantially fully converted precursor”, “fully convertedprecursor”, “converted precursor”, “substantially fully convertedpartially converted precursor”, “fully converted partially convertedprecursor”, and “converted partially converted precursor” as used hereinall describe such a thin film.

[0167] It is recognized that during the process of partially convertingand/or substantially fully converting the precursor film to the film ofthe desired material, that some shrinkage of the film may occur; thatis, the thickness of the film of the desired material is often less thanthe thickness of the unconverted precursor film. This change inthickness is an important feature of the invention, conferring usefulproperties to the film of desired material. For example, the formationof extremely thin films is advantageous with respect to maximizingcapacitance, while at the same time the formation of such thin films ischallenging from a manufacturing standpoint. The process of theinvention provides the capability to apply relatively thicker castfilms, conferring greater manufacturing ease, but also providesrelatively thinner films of the desired at least partially convertedprecursor material, conferring improved properties to the film of thedesired material. The shrinkage properties of the deposited film may becontrolled and tuned to target parameters by judicious manipulation ofprocess variables including: the selection of the precursor, theselection and quantity of the solvent, the identity of precursoradditives, the thickness of the precursor film as determined by thedeposition process, the use of thermal treatments before, during andafter the patterning of the film, and the development of the exposedfilm. The process of the invention allows for precise thickness controlof desired films ranging in total thickness from the Angstrom rangethrough the micrometer range.

[0168] After conversion, subsequent optional process steps may includepost-conversion treatment, developing, including but not limited to thenovel development method discussed above, and post-developing treatmentsteps. The specific steps chosen depend upon the ultimate use of theproduct. For example, methods of use are described in U.S. Pat. Nos.5,534,312, 5,821,017 and 6,071,676, each of which is incorporated hereinby reference in its entirety.

[0169] In certain embodiments of the present process, conversion isfollowed by an implantation step, where at least one implanted region isformed in the substrate by using an implantation means on at least aportion of the substrate substantially uncovered by the hard mask. Theuse of an ion beam as an implantation means is well known to the art.However, the present process is not limited to the use of ion beams; anyeffective method of implantation may be used. Ions suitable forimplantation include but are not limited to arsenic, boron andphosphorous. Ion implantation may be conducted under conditions of highenergy, i.e., greater than about 300 KeV, coupled with low dose, i.e.,less than about 10²⁰ atm/cm², or under conditions of low energy, i.e.,less than about 300 KeV, coupled with high dose, i.e., greater thanabout 10²⁰ atm/cm². Optionally, the hard mask layer may be removed afterimplantation. Optionally, the implanted substrate may be furthertreated, such as by annealing, thereby converting implanted substrateregions into doped regions. If both of these optional steps areperformed, the order in which they are performed may be adjusted to suitthe particular application to which the present invention is directed.

[0170] Other embodiments of the invention envision the at leastpartially converted precursor formed by the present process serving asan etch resist layer. In the etching step or steps, an etching means,such as plasma, reactive ion or wet etching solution, contacts selectedareas of the substrate through the pattern provided by the hard mask,removing substrate in those desired areas only. Currently,conventionally-applied hard masks of materials such as silicon dioxideand silicon nitride are used as protective masks in electronicsmanufacturing processes employing etching.

[0171] In addition, the PMOD™ technology has several applications toflat panel display manufacturing. Examples of such applications are (a)matrix fabrication for pixel isolation in color PLED displays; (b)deposition for permanent resist-structures for cathode patterning inpassive matrix OLED displays; (c) substrate barrier layer deposition forplastic and glass substrates; and (d) dielectric deposition for thinfilm transistor fabrication for active matrix displays.

[0172] The PMOD™ approach offers the advantage of direct thin filmimaging in examples (a) and (b) and offers material benefits forexamples (c) and (d) relating to flat panel display manufacturing.

[0173] Direct thin film imaging allows a reduction in process steps fromconventional thin film imaging. In direct thin film imaging, a PMOD™precursor film is deposited and acts as the pattern-transfer layer andhard mask. After deposition, for example, the PMOD™ precursor is exposedto UV light and developed to form a patterned PMOD™ metal/metal-oxidehard mask layer. The pattern-transfer layer may then be etched throughthe PMOD™ etch mask. In contrast, with conventional thin film imaging, aseparate hard mask layer must be deposited with a photoresist layerdeposited thereon. The photoresist layer is exposed to UV light to forma pattern to form a patterned hard mask. It is clear that the use of thePMOD™ process adds efficiency by eliminating process steps.Additionally, the PMOD™ approach may also avoid the formation of resistresidues formed from etching photoresist and the problems associatedwith the formation of such residues. The material benefits include theability to deposit metal and metal oxide barrier layers where lowtemperature processing is necessary (e.g., with plastic substrates) anda four-fold reduction in residual carbon levels from a conventionalsol-gel process.

[0174] An embodiment of the present invention is a barrier layerdeposited by the PMOD™ methodology. This approach is the directphotodeposition of a thin metal, metal oxide and/or silicate film as ahermetic barrier layer for organic substrates (e.g., plastic substrates)used in flat panel display applications. Deposition of a viable barrierlayer for plastic displays is critical for the commercialization ofdisplays on flexible substrates.

[0175] A barrier layer is critical to isolate the display devices fromimpurities present in the substrate and eliminate the permeability ofenvironmental contaminants through the substrate (e.g., water andoxygen). The efficacy of the barrier layer is critical due to thesensitivity of the cathode metal and light emitting polymer materials tooxygen and water. Both OLED and LCD manufacturers suffer from theproblem of effectively preventing contamination when fabricatingdisplays on plastic substrates. The PMOD™ based deposition of metaloxides is an effective low-temperature alternative to CVD orsputter-deposited materials.

[0176] A typical organic light emitting device 1430 is shown in FIG. 1.Organic light emitting device 1430 comprises a substrate 1432. Substrate1432 can be made from a variety of materials, including but not limitedto, glass, quartz, and plastic. Anode 1434 overlays substrate 1432. Atypical material used to make anode 1434 is indium tin oxide. A holetransport region 1436 composed of a hole transport material (HTM)overlays anode 1434, a mixed region 1438 comprising a mixture of a holetransport material and an electron transport material overlays holetransport region 1436, and an electron transport region 1440 composed ofan electron transport material (ETM) overlays mixed region 1438. Acathode 1442 overlays electron transport region 1440 and a protectivebarrier layer 1444 overlays cathode 1442.

[0177] An OLED is a current-driven device. That is, the intensity of theoutput light is directly proportional to the electrical current flowthrough the device. An OLED display, therefore, requires the control andmodulation of electrical current levels through individual elements(pixels) in order to display text or graphic images. There are twogeneral architectures for addressing pixels in an OLED: passive matrixand active matrix. Referring to FIG. 22, the passive-matrix OLED displayis formed by dividing anode layer 1434 into columns and cathode layer1442 into rows that intersect the anode columns. In typicalimplementations, the columns provide the data signal while the rows areaddressed one at a time. The current flow through a selected row istypically pulsed to a level that is proportional to a level that is afunction of the total number of rows in the display. It can be seen inFIG. 22 that barrier layer 1444 overlays the device, thereby protectingthe device from adverse environmental elements such as oxygen and watervapor.

[0178] Candidate materials include, but are not limited to, titaniumdioxide, silicon dioxide, aluminum oxide, zirconia, and silicon-dopedtitania. Also, use of other metal oxides as dopants to improve thediffusion characteristics of the materials is possible. Control of mixedmetal oxide systems is also possible through the use of the PMOD™deposition methodology.

[0179] Another embodiment of the invention envisions the at leastpartially converted precursor or hard mask formed by the present processserving as an etch resist layer. In the etching step or steps, anetching means, such as plasma, reactive ion or wet etching solution,contacts selected areas of the substrate through the pattern providedby, e.g., the hard mask, removing substrate in those desired areas only.Currently, conventionally-applied hard masks of materials such assilicon dioxide and silicon nitride are used as protective masks inelectronics manufacturing processes employing etching.

[0180]FIG. 2 illustrates the basic sequence of steps for a preferredembodiment of the process of the present invention, i.e., steps 2A, 2B,2C and 2D, which is conducted on a substrate 10 as shown in step 2Aprior to processing. Substrate 10 may be, for example, a silicon waferthat has been coated with an organic layer. In step 2B, unconvertedprecursor 11 is applied to the substrate 10. In step 2C, a convertingmeans, such as light in the photochemical metal organic depositionprocess, or thermal or heat treatment, is applied to at least oneselected portion of unconverted precursor 11 to form a convertedprecursor layer 12. In step 2D, a removing means, such as a developercomposition, is used to remove at least a portion and, preferably,substantially all, of the unconverted precursor layer 11, leaving theconverted precursor 12 intact, thereby forming a hard mask for thesubstrate 10. Such a mask suitably allows for certain patterning meansto pass into desired areas of the substrate while masking or blockingcertain other substrate areas from the patterning means.

[0181] Alternately, in step 2C of FIG. 2, a partial converting means,such as light or thermal or heat treatment, may be applied to at leastone selected portion of unconverted precursor 11 to form a partiallyconverted precursor layer 12. In step 2D, a removing means, such as adeveloper composition, is used to remove at least a portion and,preferably, substantially all, of the unconverted precursor layer 11,leaving the partially converted precursor 12 intact. A converting means,not shown, such as light or thermal or heat treatment, can then be usedon at least a portion of the partially converted precursor tosubstantially convert that portion, thereby forming a hard mask. Thepartial converting means can be the same as or different from theconverting means. FIG. 2 demonstrates the economy of steps in forming apatterned hard mask by the process of the present invention.

[0182] In contrast, FIG. 3 illustrates the far lengthier prior artmethod for forming a patterned hard mask. In step 3A, a substrate 200 issupplied as illustrated in FIG. 2. In step 3B, a hard mask layer 210 hasbeen formed on the substrate. For example, the hard mask layer may be210 silicon oxide. In step 3C, a photoresist layer 220 is applied atophard mask layer 210. In step 3D, photoresist layer 220 is exposed tolight rays 230 through mask 235. Mask 235 comprises a transparent glasssubstrate 240 having regions 250 substantially opaque to the light rays,thus blocking part of the light rays and forming a pattern on theexposed portion 222 of the photoresist layer. In step 3E, exposedphotoresist regions 222 have been developed away, thereby exposing hardmask layer 210. In step 3F, openings 255 in hard mask layer 210 havebeen formed by etching away the unprotected portions of hard mask layer210 with a suitable etching composition. In step 3G, the remainingportion of the photoresist layer 220 has been removed. In step 3H, aplasma etching chemistry 260, chosen such that it will etch thesubstrate 200 but not hard mask layer 210, patterns substrate 200. Thisresults in the patterned features 280 defined as illustrated in step 3I.Thus, it is evident from FIG. 3 that conventional processes require manymore steps for forming a patterned hard mask and, e.g., implanting ionsthrough that patterned mask, than does the process of the presentinvention.

[0183]FIG. 4 illustrates a preferred embodiment of the present processapplied to fabricating a hard mask using a metal complex precursor toform a patterned hard mask that eliminates all of the steps associatedwith hard mask etching, i.e., steps 3C through 3G described above. Instep 4A, a substrate 300 is supplied as illustrated in FIG. 2. In step4B, a layer of precursor 310, such a layer comprising a metal complex,has been formed on top of substrate 300. In step 4C, precursor 310 isexposed to a converting means and/or a partial converting means, lightrays 315 being illustrated here, directed through mask 320. Mask 320includes a transparent glass substrate 330 having regions 340substantially opaque to the partial converting means. The portion ofprecursor 310 exposed to converting means and/or partial convertingmeans 315 is at least partially converted or reacted to form regions ofpartially converted precursor 350. Preferably, precursor 310 issubstantially fully converted in step 4C. In step 4D, the assembly hasbeen exposed to a removing means (not shown) such as a liquid developer.Substantially unconverted precursor 310 has been removed by thedeveloper or removing means, exposing substrate 310, while converted orpartially converted precursor 350 which, being at least partiallyconverted, resists the removing means, remains. In optional step 4E, aconverting means (not shown) is applied to the partially convertedprecursor 350, if that precursor has not been previously substantiallyfully converted in step 4C, to form substantially fully convertedprecursor 360, i.e., a patterned hard mask. This conversion may beaccomplished, e.g., by a blanket light exposure step or a thermal orheat annealing step. In each of steps 4C and 4E, the conversion ispreferably performed in the presence of oxygen if the convertedprecursor 360 is to be a dielectric film, or in the presence of areducing gas, such as hydrogen, if the converted precursor 360 is to bea metallic film. In step 4F, an etching means, here plasma etchingchemistry 370 chosen such that it will etch the substrate 300 but nothard mask layer 360, patterns substrate 300. This results in thepatterned features 390 defined as illustrated in step 4G.

[0184]FIG. 5 illustrates a prior art method of forming a TSI in aphotoresist, for example, by the process commonly known as topsilylation imaging. In step 5A, a substrate 400 is provided. In step 5B,substrate 400 is coated with a photoresist layer 410 suitable for topsilylation. In step 5C, photoresist layer 410 is exposed to light rays430 through mask 435. Mask 435 includes a transparent glass substrate440 having regions 450 substantially opaque to the exposure means, thusblocking part of the light rays and forming a pattern on the exposedportion 432 of the photoresist layer. The exposed photoresist region 432is given different chemical and/or physical properties as a result ofthis exposure. In step 5D, the substrate 400, photoresist layer 410 andexposed photoresist regions 432 are exposed to a gaseous TSI reagent460, which selectively adsorbs to exposed photoresist regions 432,forming modified photoresist surfaces 470. Examples of TSI reagent 460well known to the art include silicon-containing gases.

[0185] In step 5E, the surface is exposed to plasma treatment 480,rendering modified photoresist surface 470 chemically more inert,thereby forming resist hard mask surface 490. In step 5F, plasmatreatment 495 removes the remaining photoresist 410 directly underneaththe resist hard mask surface 490. In step 5G, plasma treatment 497 isemployed-to pattern substrate 400 using the complex stack formed fromphotoresist layer 410, modified photoresist surface 470, and resist hardmask surface 490, to define the pattern transferred to substrate 400.The resulting pattern is illustrated by etched region 499 in step 5H. Instep 5I, a removing means (not shown) has been employed to remove thecomplex stack formed from photoresist layer 410, modified photoresistsurface 470, and resist hard mask surface 490. While the methodillustrated in FIG. 5 confers the advantages of forming thin surfacelayers for patterning, which aid in improving the resolution that can beobtained and in the relaxation of depth-of-focus demands, it suffers thedisadvantages of requiring TSI reagent 460, requiring multiple plasmatreatment steps, and involving added cost and complexity in patterntransfer not present in other conventional techniques.

[0186] In contrast, FIG. 6 illustrates a preferred embodiment of thepresent process applied to TSI using a metal complex precursor to form apatterned thin top surface. In step 6A a substrate 500, coated withpattern transfer layer 505, is provided. Pattern transfer layer 505 mayoptionally comprise an organic film-forming resins includingphotoresist, polyimide, PMMA, Novolac, epoxy, and other organic orrelated coatings known to one in the art. In step 6B, a layer ofprecursor 510 has been formed on top of substrate 500 and directly overpattern transfer layer 505. In this case, precursor 510 comprises ametal complex. In step 6C, precursor 510 is exposed to a convertingand/or partial converting means, light rays 515 being illustrated here,directed through mask 520. Mask 520 includes transparent substrate 530,exemplified as glass here, having regions substantially 540 opaque tothe converting or partial converting means. The portion of precursor 510exposed to converting and/or partial converting means 515 is at leastpartially converted or reacted to form regions of partially convertedprecursor 550. Preferably, precursor 550 is substantially fullyconverted. In step 6D, the assembly has been exposed to a removing means(not shown) such as a liquid developer. Substantially unconvertedprecursor 510 has been removed by the removing means, e.g., a developer,exposing pattern transfer layer 505, while at least partially convertedprecursor 550 which, being at least partially converted, resists theremoving means, remains. In optional step 6E, a converting means (notshown) is applied to the partially converted precursor 550, if it hasnot already been substantially fully converted, to form substantiallyfully converted precursor 560. This conversion may be accomplished,e.g., by a blanket light exposure step or a thermal or heat annealingstep.

[0187] In step 6F, the surface is exposed to an etching means 570, suchas plasma etching chemistry which is exemplified. For example, a plasmaetching means may consist essentially of oxygen. The etching meansremoves exposed areas of pattern transfer layer 505 while partiallyconverted or substantially fully converted precursor layer 560 has beenchosen and processed in such a fashion so as to render it substantiallyinert toward the etching means 570, such that etched regions 580 areformed. In step 6G, subsequent patterning (not shown) of substrate 500is effected by an etching means making use of the pattern formed inpattern transfer layer 505 underneath at least partially convertedprecursor 560 to form etched regions 590. In step 6H, a removing means(not shown) has removed all of the remaining pattern transfer layer 505and converted precursor 560, exposing the desired patterned substrate500 with etched regions 590. The method of FIG. 6 is superior to thatshown in FIG. 5 as it requires fewer steps, fewer plasma steps anddemands no TSI reagent. At the same time, the method of FIG. 6 retainsall of the advantages conferred by employing the method of FIG. 5.

[0188]FIG. 7 illustrates a prior art method of depositing a patternedmetal layer atop a substrate. This method is conventionally employedwhen the desired metal is difficult to etch, e.g., gold or platinum. Instep 7A a substrate 600 is provided. In step 7B, a release layer 605 hasbeen coated atop substrate 600, and on top of release layer 605 aliftoff layer 610 has been applied. In step 7C, optional hard mask layer620 has been deposited on top of liftoff layer 610. In step 7D,photoresist layer 630 has been applied to the top of the complex stackcomposed of optional hard mask layer 620, liftoff layer 610 and releaselayer 605. In step 7E, photoresist layer 630 is exposed to light rays645 through mask 635. Mask 635 includes a transparent glass substrate640 having regions 650 substantially opaque to the exposure means, thusblocking part of the light rays and forming a pattern on the exposedportion 632 of the photoresist layer. In step 7F, a removing means, suchas a wet developer, is applied to remove the exposed portions 632 in thephotoresist layer 630.

[0189] In step 7G, plasma etching chemistry 660 is used to etch throughoptional hard mask layer 620, if present. Plasma etching chemistry 660may also have the effect of eroding a substantial portion of thethickness of photoresist layer 630. In step 7H, plasma etching chemistry670 is used to etch through liftoff layer 610 and release layer 605. Itis possible, during this step to create sidewalls, which are preferablycurved as illustrated in step 7H, by employing plasma etching chemistry670 first in an anisotropic mode, such that charged species in theplasma move primarily in the vertical direction, and then switching toisotropic mode, in which the charged species in the plasma that areresponsible for etching move equally in all directions. The result ofthis manipulation is illustrated in step 7H. In step 71 a depositingmeans has been employed to cover the features of the surface withdesired metal 680 (e.g., gold, platinum or other desired metal). In step7J a removing means (not shown) has been employed to lift off, e.g., bya solvent treatment, all of the remaining release layer 605, liftofflayer 610, hard mask layer 620 (if present), and photoresist layer 630.This leaves behind only the desired pattern of desired metal 680 onsubstrate 600. This method of patterned metal deposition is difficult,involving many steps and requiring the use of thick layers ofphotoresist. Such thick layers require that more than a desirable amountof photoresist are consumed, which is expensive. In addition, theremoval of the photoresist is rendered more difficult by its extremethickness than would otherwise be the case.

[0190]FIG. 8, in contrast, illustrates a preferred embodiment of thepresent process applied to liftoff processing using a metal complexprecursor to form a patterned thin top surface over a liftoff layer. Instep 8A, a substrate 700 has been provided. In step 8B, substrate 700has been coated with release layer 705 and release layer 705 coated withliftoff layer 710. In step 8C, precursor layer 720 is coated overliftoff layer 710. In this case, precursor 720 comprises a metalcomplex. In step 8D, precursor 720 is exposed to a converting and/orpartial converting means, here light rays 745 are exemplified, directedthrough mask 735. Mask 735 includes a transparent glass substrate 740having regions 750 substantially opaque to the converting and/or partialconverting means. The portion of precursor 720 exposed to the convertingand/or partial converting means 745 is at least partially converted orreacted to form regions of at least partially converted precursor 732.Preferably, precursor 732 is substantially fully converted. In step 8E,the assembly has been exposed to a removing means (not shown) such as aliquid developer. Substantially unconverted precursor 720 has beenremoved by the developer or removing means, exposing liftoff layer 710,while at least partially converted precursor 732 which, being at leastpartially converted, resists the removing means, remains. In an optionalstep (not shown), a converting means (not shown) is applied to thepartially converted precursor 732 to form substantially fully convertedprecursor, if precursor 732 has not already been substantially fullyconverted. In step 8F, removing means 760, for example, plasma etchingchemistry, is employed in an anisotropic fashion to remove those areasof liftoff layer 710 and underlying release layer 705 not underneathprecursor 732. In step 8G, a liftoff curved profile, e.g., asillustrated, is formed by allowing removing means 760 to isotropicallyetch. liftoff layer 710 and release layer 705. In step 8H, a film of thedesired metal 770 is deposited by a depositing means over the assembly.In step 8I, unwanted portions of desired metal 770 are removed alongwith precursor 732, liftoff layer 710 and release layer 705, by adeveloping means, for example solvent or dry development process,leaving behind the desired pattern of desired metal 770 on top ofsubstrate 700. This method is preferable to the prior art methodoutlined in FIG. 7 as it requires fewer process steps and does notrequire the use of a photoresist.

[0191]FIG. 9 illustrates yet another preferred embodiment of the presentprocess applied to liftoff processing using a metal complex precursor toform a patterned thin top surface film over a liftoff layer. In step 9Aa substrate 800 is provided. In step 9B, precursor layer 810 is coatedover substrate 800. In this case, precursor 810 comprises a metalcomplex. In step 9C, precursor layer 810 is exposed to a convertingmeans and/or partial converting means, here light rays 845 areexemplified, directed through mask 835. Mask 835 includes a transparentglass substrate 840 having regions 850 substantially opaque to theconverting and/or partial converting means. The portion of precursor 810exposed to converting and/or partial converting means 845 is at leastpartially converted or reacted to form regions of exposed regions 832.In step 9D, the assembly has been exposed to a removing means (notshown) such as a liquid developer. Substantially unconverted precursor810 has been removed by the removing means, exposing substrate 800,while exposed regions 832 which, being at least partially converted,resists the removing means, remains. Optionally, as described in otherpreferred embodiments of the invention, the exposed regions 832 may besubjected to further conversion after the removing means step 9D if theyhave not been previously substantially fully converted. Theinwardly-tapering sidewall profiles present in exposed regions 832, asillustrated in step 9D, are obtained by the appropriate control over theexposure and removing means represented in steps 9C and 9D,respectively, e.g., as described in steps 8D, 8F and 8G above. In step9E, a film of the desired metal 870 is deposited by a depositing meansover the assembly. In step 9F, unwanted portions of desired metal 870are removed along with precursor 832 by a developing means, for examplesolvent or dry development process, leaving behind the desired patternof metal 870 on top of substrate 800.

[0192] In another preferred embodiment of the present process, the useof TSI layer,, integration can be used to construct dual damascenearchitectures for copper integration into semiconductor interconnectstructures. FIG. 10, steps A through H, illustrates one prior art methodof constructing a damascene architecture, referred to as the “via-first”method. In step 10A, a substrate 900 is provided, which has been coatedsuccessively as indicated with a first dielectric layer 905, a barrierlayer 915, a second dielectric layer 910, and a hard mask 920. Thedielectric layers 905 and 910 are commonly but not necessarily the samematerial, while the barrier and hard mask layers 915 and 920 may or maynot be the same material, but are frequently either silicon nitrideand/or silicon oxide. In step 10B, the assembly has been coated, atophard mask 920, with a bottom anti-reflective-coating (“BARC”) 925 andphotoresist layer 930. As illustrated, the photoresist layer has beenpatterned and developed by conventional methods. In step 10C, plasmaetching chemistry has been used to remove the indicated portions of BARClayer 925, hard mask 920, dielectric layer 910, barrier layer 915, anddielectric layer 905. In step 10D, remaining photoresist 930 and BARC925 have been removed from the assembly following the plasma process ofstep 10C. In step 10E, a second BARC layer 935 and second photoresistlayer 940 have been applied to the assembly atop hard mask 920; asillustrated, photoresist layer 940 has been patterned and developed byconventional methods. In step 10F, a second plasma etching chemistrystep has been used to remove the indicated portions of BARC layer 935and dielectric layer 910. In step 10G, remaining photoresist 940 andBARC 935 have been removed following the plasma process of step 10F.

[0193] In contrast, FIG. 11 illustrates how a process of the inventionmay accomplish the assembly of a dual damascene architecture with manyfewer process steps. In step 11A, a substrate 1000 coated withdielectric layer 1005 is provided. In step 11B, a precursor layer, e.g.,comprising a metal complex, has been applied atop the dielectric layer,patterned by at least partial conversion and, preferably, substantiallyfull conversion, and then developed by techniques such as thosediscussed previously in other embodiments of the invention to yieldpatterned layer 1010 as illustrated. For example, the patterndevelopment step can be performed by, e.g., solvent or dry developmentprocess, as described above. A spin planarization layer 1015 is thenapplied atop patterned layer 1010. The spin planarization layer 1015 maybe any organic-based coating that can be spun on to the assembly. Instep 11C, a second patterned layer 1020 has been deposited, patternedand developed as illustrated, e.g., using techniques identical to thoseemployed in the formation of patterned layer 1010. In step 11D, anetching means (not shown), such as plasma etching chemistry, has beenemployed to remove the illustrated region of spin planarization layer1015 and a portion of the thickness of dielectric layer 1005. It isimportant that the etching means be controlled such that only part ofthe thickness of dielectric layer 1005 is removed, as shown. Forexample, plasma etching exposure limited to a time less than would berequired to etch: through the entire dielectric layer thickness can beused.

[0194] In step 11E, patterned layer 1020 and spin planarization layer1015 have been removed by a removing means, such as treatment of theassembly with a solvent in which spin planarization layer 1015 issoluble and which does not have substantially deleterious effect onother parts of the assembly. In step 11F, a controlled etching means(not shown), such as the plasma etching chemistry described above, hasbeen employed to remove the illustrated region of dielectric layer 1005.This controlled etch simultaneously removes the remaining thickness ofdielectric layer 1005 in the pattern formed by patterned layer 1020 butonly removes part of the thickness of dielectric layer 1005 in thepattern formed by patterned layer 1010. A dual damascene mold can beassembled in this fashion.

[0195] Patterned layer 1010 may optionally be removed following step 11F(not shown); alternately, it is a further embodiment of the inventionthat the patterned layer 1010 remain to be employed as a CMP stopfollowing copper deposition and planarization.

[0196] It is evident that the process illustrated in FIG. 11 is superiorto the prior art method illustrated in FIG. 10, as the former involvesmany fewer process steps, does not require multiple photoresist and BARCsteps, and obviates the need for the barrier and hard masks employed inconventional processes.

[0197]FIG. 12 illustrates the complex method of implanting ionsfacilitated by prior art methods for forming a patterned ion implantmask. In step 12A, a substrate 1200 is supplied as illustrated in FIG.2. In step 12B, an optional protective layer 1205 has been formed onsubstrate 1200 followed by implant mask layer 1210. In one example,implant mask layer 1210 is a silicon oxide. In step 12C, a photoresistlayer 1220, is applied to the substrate 1200 on top of implant masklayer 1210. In step 12D, photoresist layer 1220 is exposed to light rays1230 through mask 1235. Mask 1235 includes a transparent glass substrate1240 having regions substantially opaque to the exposure means 1250,thus blocking part of the light rays and forming a pattern on theexposed portion 1222 of the photoresist layer. In step 12E, exposedphotoresist regions 1222 have been developed away exposing implant masklayer 1210. In step 12F, openings 1255 in implant mask layer 1210 havebeen formed by etching away the unprotected portions of implant masklayer 1210 with a suitable etching composition. In step 12G, theremaining portion of the photoresist layer 1220 has been removed. Instep 12H, substrate 1200 is exposed to ion beam 1260 in order to formimplanted regions 1270 directly under openings 1255 in the implant mask.In optional step 12I, the implant mask layer 1210 has been removed andthe substrate annealed, thereby converting implanted regions 1270 intodoped regions 1280. Thus, it is evident from FIG. 12 that conventionalprocesses require many steps for forming a patterned implant mask and,e.g., implanting ions through that patterned mask, than does the processof the present invention.

[0198] In contrast, FIG. 13 illustrates another preferred embodiment ofthe present process applied to fabricating an ion implantation hard maskusing a metal complex precursor to form a patterned implant mask thateliminates all of the steps associated with implant mask etching, i.e.,steps 12C through 12G described above. In step 13A, a substrate 1300 issupplied. In step 13B, an optional protective layer 1312 has been formedon substrate 1300 and a layer of precursor 1310 has been formed on topof protective layer 1312. In this case, precursor 1310 is a metalcomplex. In step 13C, precursor 1310 is exposed to a converting and/orpartial converting means, here, light rays 1315 directed through mask1320. Mask 1320 includes a transparent glass substrate 1330 havingregions 1340 substantially opaque to the partial converting means. Theportion of precursor 1310 exposed to converting and/or partialconverting means 1315 is at least partially converted or reacted to formregions of partially converted precursor 1350. In step 13D, the assemblyhas been exposed to a removing means (not shown) such as a liquiddeveloper. Unconverted precursor 1310 has been removed by the developeror removing means, exposing protective layer 1312, while partiallyconverted precursor 1350 which, being partially converted, resists theremoving means, remains. In optional step 13E, a converting means (notshown) is applied to the partially converted precursor 1350, if apartial converting means was used in step 13C, to form substantiallyfully converted precursor 1360. This conversion may be accomplished,e.g., by a blanket light exposure step or a thermal annealing step. Ineach of steps 13C and 13E, the conversion is preferably performed in thepresence of oxygen if the converted precursor 1360 is to be a dielectricfilm, or in the presence of a reducing gas, such as hydrogen, if theconverted precursor 1360 is to be a metallic film. In step 13F,substrate 1300 is subjected to an implantation means, such as an ionbeam 1370, in order to form implanted regions 1380 in the substrate. Inoptional step 13G, the implant mask has been removed and a thermalannealing process performed in order to convert implanted regions 1370into doped regions 1390 in the substrate.

[0199] The broad scope of the process of the present invention allowsfor a wide range of possible applications. A preferred embodiment of theinvention comprises an amorphous metal oxide film used to form anintegral capacitive structure within a printed wire board (“PWB”),wherein a PWB substrate is coated and directly imaged by the presentprocess using an appropriate precursor solution. Advantages of thepresent invention include the ability for direct imaging and associatedelimination of other process steps, the use of ambient temperatures andpressures required for PWB processing, and the formation of films withacceptably high capacitance.

[0200] In another preferred embodiment, a patterned metal oxide or amixed metal oxide film is formed, by the present process, into an opaquepattern on a transparent substrate. Such implements may be used aspatterning masks for the lithographic transfer of patterns during thesemiconductor manufacturing process.

[0201] In yet another preferred embodiment of the invention, anamorphous metal oxide or mixed metal oxide film is used to form adecoupling capacitive structure within the interconnect levels of anadvanced interconnect semiconductor device wherein a modified siliconsubstrate is coated and directly imaged by the present process with anappropriate precursor solution. Advantages implicit in this embodimentinclude the ability for direct imaging, thereby eliminating many otherprocess steps, and the use of ambient temperatures and pressures nototherwise available in the assembly of such advanced interconnects.

[0202] A further preferred embodiment of the invention envisions the useof precursor films that may be used to pattern memory storage elementsin either capacitive storage nodes, i.e., dynamic random access memory(“DRAM”), or as ferroelectric memory storage nodes (“FeRAM”). Again,advantages implicit in this embodiment include the ability for directimaging, thereby eliminating many other process steps, and the use ofambient temperatures and pressures not otherwise available in theassembly of such memory devices.

[0203] Yet another preferred embodiment of the invention envisions theformation of gate dielectric materials at the front end of semiconductormanufacture, as advanced silicon-based devices make a transition in thepreferred gate dielectric material, from silicon dioxide to newmaterials having a higher dielectric constant. The new higher dielectricconstant materials allow the gate dielectric to be made physically thickrelative to silicon dioxide for equivalent electrical properties. Thisgreater physical thickness can allow for greater ease of manufacture andminimized quantum tunneling effects through the gate. That the processof this invention has major advantages over other known processes interms of lower temperatures and less stringent vacuum processingrequirements is highly significant when applied to front end of the line(“FEOL”) semiconductor processing. A wide variety of high dielectricconstant materials are amenable to the process of the invention,including but not limited to Ba_(x)Sr_(y)Ti_(z)O₃ (“BST”), BaTiO₃,SrTiO₃, PbTiO3, Pb_(x)Zr_(y)Ti_(z)O₃ (“PZT”), (Pb, La)(Zr, Ti)O₃(“PLZT”), (Pb, La)TiO₃ (“PLT”), LiNbO₃, Ta₂O₅, SrBi₂Ta₂O₉, Al₂O₃, TiO₂,ZrO₂, HfO₂, and perovskite materials.

[0204] Similarly, the invention may be employed to fabricate gateelectrode materials for FEOL semiconductor manufacture. These materialsrest atop the gate dielectric forming an electrical contact to the gatedielectric. Historically, gate electrodes have been constructed fromsilicon. In an analogous fashion to the migration of gate dielectricmaterial away from silicon dioxide, there is impetus to transition gateelectrodes to materials having substantially better performancecharacteristics than silicon. Candidate materials for gate electrode useinclude platinum, iridium, ruthenium, ruthenium oxide, iridium oxide andother new materials. All of these materials are conventionallychallenging to deposit and pattern, however, they are amenable to use inthe present process. Additionally, many of the steps in conventionalmethods invoke high temperatures, stringent vacuum requirements, and theuse of harsh plasma processing conditions, which threatens to damage thesensitive silicon substrate. Such harsh conditions can be avoided byemploying the process of the present invention. More challenging stillfor conventional processes is the need for different electrode materialsto be placed over gate transistors of different bias, as described inU.S. Pat. No. 6,048,769. This requirement for conventional integrationpaths doubles an already large number of steps; hence this preferredembodiment of the invention provides dramatic advantages, from amanufacturing standpoint, to lower this large number of steps.

[0205] The applicability of noble metals and conducting metal oxides isnot limited to gate electrode formation. There are several barrier layerapplications for such materials, both as the conducting and insulatinglayers that are mandated in FEOL semiconductor processing. It is evidentthat several of these applications rely on the formation of a film ofthe desired material that has a high dielectric constant (“high-k”) foruse as a capacitive material. In a similar fashion, films may beoptimized so as to optimize the film's permeability (u) for use as aninductor material. Resistive elements are similarly possible, as aremagnetic, piezoelectric, pyroelectric and ferroelectric elements.

[0206] Other possible applications for the process of the presentinvention are wide and varied. Some examples include: direct patterneddeposition of high dielectric constant materials for semiconductormanufacturing (transistor gate stack, capacitive structures, etc.);direct patterned deposition of high dielectric constant materials formicroelectronics packaging (capacitive structures); low temperaturedeposition of high dielectric constant materials for semiconductormanufacturing (transistor gate stack, capacitive structures, etc.); lowtemperature deposition of high dielectric constant materials formicroelectronics packaging (capacitive structures, etc.); non-vacuumbased deposition of high dielectric constant materials for semiconductormanufacturing (transistor gate stack, capacitive structures, etc.);non-vacuum based deposition of high dielectric constant materials for;microelectronics packaging (capacitive structures, etc.); directpatterned deposition of metal oxides for semiconductor manufacturing(insulator structures, etc.); direct patterned deposition of metaloxides for microelectronics packaging; low temperature deposition ofmetal oxides for semiconductor manufacturing; low temperature depositionof metal oxides for microelectronics packaging (capacitive structures,etc.); non-vacuum based deposition of metal oxides for semiconductormanufacturing; non-vacuum based deposition of metal oxides formicroelectronics packaging; direct patterned deposition of metals forsemiconductor manufacturing (transistor gate stack); direct patterneddeposition of metals for microelectronics packaging (interconnects,etc.); low temperature deposition of metals for semiconductormanufacturing; low temperature deposition of metals for microelectronicspackaging; non-vacuum based deposition of metals for semiconductormanufacturing; non-vacuum based deposition of metals formicroelectronics packaging; direct patterned deposition of resistivematerials for semiconductor manufacturing (on-chip resistive elements);direct patterned deposition of high resistive materials formicroelectronics packaging (embedded resistors); low temperaturedeposition of resistive materials for semiconductor manufacturing; lowtemperature deposition of resistive materials for microelectronicspackaging (embedded resistors); non-vacuum based deposition of resistivematerials for semiconductor manufacturing; non-vacuum based depositionof resistive materials for microelectronics packaging; controlledresistivity materials via mixed metal/oxide deposition; direct patterneddeposition of materials for inductor fabrication in semiconductormanufacturing (on-chip inductors); direct patterned deposition ofmaterials for inductor fabrication for microelectronics packaging(embedded inductors); low temperature deposition of materials forinductor fabrication for semiconductor manufacturing; low temperaturedeposition of materials for inductor fabrication for microelectronicspackaging (embedded inductors); non-vacuum based deposition of materialsfor inductor fabrication for semiconductor manufacturing; non-vacuumbased deposition of materials for inductor fabrication formicroelectronics packaging; direct patterned deposition of metal andoxide materials for fabrication of devices using organic semiconductorsand/or organic substrates; low temperature deposition of metal and oxidematerials for fabrication of devices using organic semiconductors and/ororganic substrates; non-vacuum based deposition of metal and oxidematerials for fabrication of devices using organic semiconductors and/ororganic substrates; use as a photosensitive, e-beam sensitive layer in abilayer or TSI photoresist process; directly patterned, low temperature,non-vacuum based deposition of magnetic materials; deposition of mixedmetal and mixed oxide materials; screen printing of metal and metaloxide structures; inkjet-like (droplet) printing of metal and metaloxide structures; spray coating of metal/oxide films on surfaces; use ofthese materials to allow for liquid phase coating (spin-coating ormeniscus coating) of thick films to simplify and improve the coatingprocess and performance and then making use of the volume shrinkage uponconversion to result in thin coatings (such an application is in theformation of embedded capacitors where thick layers are coated thatproduce thin final films to improve the capacitance of the structures);liquid coating and subsequent photochemical or low temperature thermalconversion of organometallic precursors to deposit metal or metal oxidecoatings on polymer/natural fibers (coat silver/silver oxide for examplefor anti-microbial fibers and textiles for hospital use, odor resistantgarments such as socks or pads); liquid infiltration and subsequentthermal conversion of precursors to form catalytically active porousmaterials; use as an additive to polymer solutions to modify thephysical, chemical, optical, and electrical properties of the resultingmaterial by forming nanocomposites; synthesis and formulation of watersoluble precursors to reduce VOC emissions from the processes mentionedabove; gate electrode materials; flat panel displays; FeRAM;direct-write materials; microfluidics; masks; and waveguides.

[0207] Additional descriptions of processes for the fabrication ofelectronic materials include those described in concurrently-filed U.S.patent application Ser. No. 09/874,330, entitled “Method of andApparatus for Substrate Pretreatment,” the disclosure of which isincorporated herein by express reference thereto.

EXAMPLE

[0208] The following examples further illustrate certain embodiments ofthe present invention. These examples are provided solely forillustrative purposes and in no way limit the scope of the presentinvention.

Example 1

[0209] Two films of different zirconium-containing precursors,Zr(acetylacetonate)₄ (also known as Zr(acac)₄ andtetrakis(2,4-pentanedionato)zirconium(IV)) and Zr(carboxylate)₄ werecast by dissolving them in a suitable solvent and spin-coating thesolution onto the surface of a silicon wafer. Each was subjected toprolonged blanket thermal treatment, i.e., until there were no furtherchange in precursor film thickness. Following this treatment, therefractive index of each sample was measured as a function of wavelengthusing variable angle spectroscopic ellipsometry (“VASE”). The resultsare illustrated in FIG. 14. In FIG. 14, line 101 is from the sampleformed from the Zr(acac)₄ precursor and line 102 is from the sampleformed from the Zr(carboxylate)₄ precursor. These results demonstratethat there are significant differences in the refractive indexproperties for each of the samples which are directly related to thechemical composition of the precursor. The Zr(acac)₄ precursor forms afilm with a refractive index about 3% greater than a film formed fromZr(carboxylate)₄.

Example 2

[0210] Two different copper precursors were initially prepared,Cu₂(OH₂)₂(O₂C(CH₂)₄CH₃)₄ and (μ-(C₂H₅)₂NCH₂CH₂O)₂Cu₂(N₃)₂. Eachprecursor is thought to undergo a photochemical reaction, which leads tothe loss of the ligands and the production of copper atoms. The copperatoms are then thought to combine with each other to form either coppermetal or to combine with oxygen to form copper oxide, however, theformation of the oxide may also occur as a result of the oxidation offirst-formed copper metal. Based on the chemical prior art, there is noreason to postulate that these different precursors would providedifferent products under similar reaction conditions, although it hasbeen recognized that the film forming properties and the efficiency ofthe reactions may vary widely as a result of the choice of precursor.

[0211] Accordingly, each of these two precursors was dissolved, eachsolution was deposited on silicon chips by spin-coating, and theprecursor layer on each of the coated chips was substantially fullyconverted by photolysis with light in a vacuum. Photolysis was continueduntil no absorption associated with the ligands was observed in the FTIRspectra of the films. The samples were then transferred to a furnace andheated under nitrogen at 400° C.

[0212] Subsequently, each sample was examined by the well-knownwide-angle x-ray diffraction method. It was found that theCu₂(OH₂)₂(O₂C(CH₂)₄CH₃)₄ precursor yielded more copper oxide afterconversion while the (μ-(C₂H₅)₂NCH₂CH₂O)₂Cu₂(N₃)₂ precursor yielded morecrystalline metallic copper. These results demonstrate the dependence ofthe outcome of the process, i.e., after conversion, on the precursorcomposition in a way not previously envisioned by the art.

[0213] The method by which a film of a given precursor material isconverted to an amorphous film, e.g., by a thermal or photolyticprocess, can have a significant impact, on the film's properties. Thisis shown in the data summarizing optical refractive index, and is alsoclearly demonstrated by a comparison of dielectric constant data, asillustrated in Examples 3 and 4.

Example 3

[0214] The precursor Zr(acac)₄ (zirconium(IV) acetylacetonate fromChemat Technology, Inc., Northridge, Calif.) was dissolved in tolueneand the solution was spun onto silicon wafers at 1250 rpm for 30seconds. The resulting unconverted precursor film had a thickness of 436Å. Thermal conversion to ZrO₂ was carried out on a hotplate at 180° C.for 1 hour. Extended thermal conversion was carried out on a hotplate at180° C. Photochemical conversion to ZrO₂ was carried out using a KarlSuss MJB-3 mask aligner with a 220 nm cold mirror. Due to the lowintensity output of the mask aligner in the deep UV (about 0.38 mW/cm²),an exposure time of 5 hours was used because this was found to be thedose where additional exposure does not lead to further thicknessreduction. The thickness and refractive index a function of wavelengthfor the resulting films were measured using VASE. The measured thicknessof these films were as follows: Unconverted Zr(acac)₄ Precursor 436 ÅThermally Converted 360 Å Extended Thermal Conversion 316 ÅPhotoconverted 330 Å

[0215] The precursor Zr(O(O)CC₇H₁₅)₄ (zirconium(IV) 2-ethyl hexanoate,from Chemat Technology, Inc., Northridge, Calif.) was dissolved inhexanes and the solution was spun onto silicon wafers at 1500 rpm for 30seconds. The resulting unconverted precursor had a thickness of 2335 Å.Thermal conversion to ZrO₂ was carried out on a hotplate at 180° C. for3 hours. Extended thermal conversion was carried out on a hotplate at180° C. for a total of 6 hours, which includes the thermal conversiontime of 3 hours. Photochemical conversion to ZrO₂ was carried out asdescribed above for the ZrO(acac)₂ precursor except that, because of thelow photosensitivity of the Zr(O(O)CC₇H₁₅)₄ precursor and the lowexposure intensity, an exposure time of about 30 hours was used. Again,the thickness and refractive index as a function of wavelength for eachresulting film was measured using VASE. The measured thickness of thesefilms were as follows: Unconverted Zr(O(O)CC₇H₁₅)₄ Precursor 2335 ÅThermally Converted 1141 Å Extended Thermal Conversion  977 ÅPhotoconverted 1487 Å

[0216] The refractive index results are shown in FIG. 15, whereZr(acac)₄ photochemically converted is line 1, Zr(acac)₄ thermallyconverted is line 2, Zr(O(O)CC₇H₁₅)₄ thermally converted is line 3,Zr(O(O)CC₇HI₅)₄ photochemically converted is line 4, Zr(O(O)CC₇H₁₅)₄converted by an extended thermal conversion is line 5, and Zr(acac)₄converted by an extended thermal conversion is line 6.

[0217] These results demonstrate that there are significant differencesin the refractive index properties for each of the samples which aredirectly related to the chemical composition of the precursor and to themethod by which it was prepared.

Example 4

[0218] Aluminum-coated silicon wafers were spin-coated withapproximately 7000 Å of a precursor designed to yield BST after at leastpartial conversion, in solution in hexanes. The precursor films of BSTwere prepared by dissolving 3.7 gTi(bis(acetylacetonate)di(isopropoxide)), 2.8 g barium 2-ethylhexanoateand 5.6 g 2-ethylhexanoate (40% w/w in 2-ethylhexanoate acid) in 182 ghexanes, corresponding to a Ba:Sr:Ti(IV) molar ratio of 1:0.8:1. Theprecursor films were converted into BST films by either thermaltreatment or photolytic treatment. The resulting thin BST films werefabricated into thin-film capacitors and film electrical properties weremeasured. The dielectric constant and average conductance value of eachfilm differed dramatically, as can be seen from the following results:BST from Thermal Conversion Dielectric Constant  4.66 AverageConductance  0.009992 μS BST from Photochemical Conversion DielectricConstant 27.26 Average Conductance  0.04311 μS

[0219] These results demonstrate that there are significant differencesin the electrical properties for each of the samples which are directlyrelated to the method by which the converted precursor was prepared.

Example 5

[0220] The choice of solvent in, for example, the spin-coating of filmprecursors, is an important because it may influence the optical qualityof the film. For instance, this example demonstrates that casting of afilm comprising precursors designed to be converted to BST yielded filmsof high optical quality from a solution in each of MIBK and n-heptane,while “streaky” films were formed from a solution of PGMEA.

[0221] Precursor solutions were formed in each of these three solventsby either dissolving the precursors in the solvent or replacing some orall of the solvent in the precursor solution with the desired solvent.Each solution was deposited onto an aluminum-covered Si wafer byspin-coating. The wafers were spun at 1500 rpm for 30 seconds. Spinningwas followed by a bake on a hotplate at 110° C. for 2 minutes to removeany remaining solvent. The precursor films were converted to the oxideis using a Karl Suss MJB-3 mask aligner with a 220 nm cold mirror at anintensity of about 1.2 mW/cm 2. Each wafer was exposed for 1.5 hours toensure complete conversion. After conversion, a development or removalstep was performed in which the unconverted, unexposed portions of eachprecursor film were washed off by rinsing with the same solvent used inspin-coating that sample. Film thicknesses before conversion, i.e.,unconverted, immediately after conversion, and after development weremeasured using VASE.

[0222] A precursor film of high optical quality, such as those producedfrom MIBK and n-heptane, had a surface which is essentially featureless;therefore, no figures are included to show this. In contrast, the BSTprecursor film spin-coated from the PGMEA solution showed significantstreaking, as can be seen from FIG. 16. Of the above solvents, MIBKproduced the most uniform and reproducible films.

Example 6

[0223] In an example of how thermal treatment may be used to convert aprecursor film to an amorphous film of desired material, a series ofbare silicon wafers was spin-coated with a solution of precursordesigned to form BST upon conversion. The wafers were subjected to atleast a partial conversion step by heating each on a hotplate at 160° C.for a total time of 120 minutes in intervals of 10 minutes. After eachconversion interval, the precursor pattern was developed by rinsing withisopropanol to remove the unconverted precursor. This allowed for adetermination of the time required to thermally print the film, i.e., tohave a substantial amount of film remaining after development with IPA.As shown in the FIG. 17, this time was determined to be approximately 20minutes for thermal conversion.

[0224] A similar experiment was conducted by substituting, for thermalconversion, photochemical conversion; these results are shown in FIG.18. This figure demonstrates that the time required to photochemicallyprint the film was in the range of 30 to 60 minutes. In a thirdexperiment, designed to combine thermal partial conversion orpretreatment with photochemical conversion, wafers were subjected to athermal pretreatment of 160° C. for 10 minutes, then subjected to theabove-described photochemical conversion procedure. Thethermal/photochemical print results are illustrated in FIG. 19, whichdemonstrates that the time required for conversion by the combinedthermal/photochemical conversion process, i.e., about the minimum timeneeded to form a pattern, has been reduced to approximately 20 minutesfrom 30 to 60 minutes for photochemical conversion alone.

Example 7

[0225] The resolution of an optical projection system can be improved byreducing the wavelength of the imaging light and by increasing thenumerical aperture of the lens system. However, the ability to keep theimage in focus throughout the resist decreases as its thicknessincreases. The depth of focus can be maintained by decreasing thethickness of the resist film, however, the minimum resist thickness islimited by the etch requirements needed for pattern transfer steps. Inorder to alleviate depth of focus limitations, thin film imaging hasbeen used to pattern only the top layer of the resist. After imaging theresist top layer, the pattern is developed and then transferred to thesubstrate using an etch process.

[0226] For a bilayer approach using metal complex precursors, a twostack film comprising an underlayer and a metal complex precursor can beused, with each layer, e.g., spin-coated. The metal complex precursorserves the need for an etch mask while the underlayer is used totransfer the pattern to the substrate by etching. Three differentunderlayers were tested: PMMA, PHOST and Novolac. PHOST and Novolac werehard baked on the hotplate at 160° C. for 2 hours prior to spin-coatingof the metal complex precursors. The metal complex precursors used inthe experiment were designed to form BST, PZT or titanium dioxide(TiO₂). The BST precursor was prepared according to the proceduredescribed in Example 4. The PZT precursor was prepared by dissolving18.48 g of lead(II) 2-ethylhexanoate in 57.4 g hexanes and adding 24.2 gzirconium(IV) 2-ethylhexanoate and 9.5 gTi(bis(acetylacetonate)di(isopropoxide)) followed by the addition of 327g of additional hexanes, corresponding to a Pb(II):Zr(IV):Ti(IV) molarratio of 2.5:1:1.3. The following table lists the different combinationsused and whether the underlayer and metal complex precursor were deemedto be compatible. Relative Compatibility Using Underlayer PrecursorHexanes Casting Solvent PMMA BST Poor PMMA PZT Poor PHOST BST Poor PHOSTPZT Poor Novolac BST Good Novolac PZT Good Novolac TiO₂ Good

[0227] Hard baked Novolac was found to be compatible with BST, PZT andTiO₂ precursors, while the PMMA and PHOST underlayer materials testeddissolved during spin-coating of the metal complex layer. PMMA and PHOSTdissolved away in the presence of the casting solvent hexanes used forthe BST and PZT precursors. The compatibility of hard baked Novolac withBST and PZT precursors allowed for patterning and transfer of thepattern.

Example 8

[0228] The etch selectivity between the hard baked Novolac and two metalcomplexes was determined by monitoring the thickness change uponetching. The samples of hard baked Novolac and a fully converted PZT orTiO₂, prepared according to Example 7, were loaded into the etchingchamber and etched with an oxygen plasma for 30 second intervals up to atotal of at least 120 seconds. The sample thickness was measured aftereach etch interval. The etch rate for each sample was determined fromthe slope of a plot of thickness versus etching time. Plots of thicknessversus etching time of hard baked Novolac is shown in FIG. 20 while thesame plots are shown in FIG. 21 for fully converted PZT and TiO₂. Thefollowing table lists the respective slopes and correlation coefficientsof the linear least-squares lines. Layer Being Slope of ThicknessCorrelation Oxygen Etched v. Etching Time Plot Coefficient Hard Baked−76.3 0.999 Novolac Fully −0.195 0.985 Converted PZT Fully −0.0866 0.992Converted TiO₂

[0229] The etch selectivity was determined from the ratio of the slopeof the respective etch rate plots. The etch selectivity between hardbaked Novolac and fully converted PZT is about 390:1. The etchselectivity between hard baked Novolac and fully converted TiO₂ is about880:1. The etch selectivity of TiO₂ is comparable with that of SiO₂under the same conditions.

Example 9

[0230] E-Beam contrast of BST and PZT was performed to determine thephotospeed of these materials by exposing a series of fully convertedfilms of each material to increasing doses of the e-beam and noting,after development, the highest dose at which the fraction of filmremained at zero and the lowest dose at which the fraction of filmremaining reached a value of about 1. The contrast for PZT and BSToccurs at about the same range for each, from about 60 to about 100μC/cm².

Example 10

[0231] Titanium dioxide deposited at low temperature (less than 40° C.)using PMOD methodology (refractive index of 2.05 at 630 nm) has adensity approximately 90% that of crystalline (anatase phase) titaniumdioxide (refractive index of 2.3 at 630 nm). Density has been shown tobe a function of precursor structure, UV conversion, and post-UVconversion processing. Post-UV conversion processing at temperaturesless than 300° C. has resulted in patterned deposition of titaniumdioxide with a density 95% that of crystalline (anatase phase) titaniumdioxide (refractive index of 2.16 at 630 nm).

Example 11

[0232] The following procedure was used to deposit a barrier layer. A100-mm silicon wafer was spin coated using a CEE Model 100CV spin coaterwith TOK OFPR 800 20 photoresist at 5000 rpm over 20 seconds. The filmwas baked on a hot plate at 230° C. for 5 minutes on a MTI FlexiFabsystem. This yielded a film of approximately 5000 Å. A layer of PMODTiO₂ precursor (Ti(O(CH₂)₃(CH₃))₂(OOCCH(CH₂CH₃)(CH₂)₃CH₃)₂) was spincoated on the photoresist. The PMOD precursor was converted using aconveyor type UV curing unit (UVESX Model CCU, 2 passes) resulting in aPMOD TiO₂ film of 170Å. The coated substrate was then subjected to anoxygen plasma using a Branson/IPC P2100 Nonprecision Barrel System(P(O₂)=1 torr, 1000W, 30 minutes). The PMOD TiO₂ layer was then removedby immersion in CuSolve™ EKC 5800™ Cu in a static bath for 10 minutes atroom temperature. After processing, the substrates are rinsed in DIwater and dried in a nitrogen gas stream. The surface of the photoresistwas examined using Scanning Electron Microscopy (FEI XL 830 SEM/FIB).The samples were coated using a Denton Vacuum Desk II sputter tool withgold to prevent charging in the SEM and the images obtained using anaccelerating potential of 10 keV.

[0233] The experiment was repeated with three layers of PMOD TiO₂ (totalPMOD TiO₂ thickness of approximately 500Å). The use of multiple layerswas used to minimize defects that could compromise the barrier layer.Using multiple layers of the PMOD TiO₂ shows elimination of defects inthe polymer film after exposure to an oxygen plasma.

[0234] One skilled in the art will appreciate that the scope of thepresent invention is not limited to that which is expressly disclosedherein but includes extensions.

[0235] All references cited herein are incorporated herein by referencein their entirety and for all purposes to the same extent as if eachindividual publication or patent or patent application was specificallyand individually indicated to be incorporated by reference in itsentirety for all purposes. While the present invention has beendescribed with reference to a few specific embodiments, the descriptionis illustrative of the invention and is not to be construed as limitingthe invention. Various modifications may occur to those skilled in theart without departing from the true spirit and scope of the invention asdefined by the appended claims.

What is claimed is:
 1. A method of forming a barrier layer on asubstrate comprising the steps of: selecting at least one precursormaterial; forming an amorphous layer comprising the precursor atop asubstrate; converting at least a portion of the precursor layer; anddeveloping the precursor layer.
 2. The method of claim 1, furthercomprising developing away an unconverted portion of the precursor layerwith a developer.
 3. The method of claim 1, wherein the substrate isflexible.
 4. The method of claim 3, wherein the substrate is plastic. 5.The method of claim 1, further comprising selecting the at least oneprecursor material from a metal complex comprising at least one ligandselected from the group consisting of acac, carboxylato, alkoxy, azide,carbonyl, nitrato, amine, halide, nitro, and mixtures thereof and atleast one metal selected from the group consisting of Li, Al, Si, Ti, V,Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn,Ba, La, Pr, Sm, Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As,Ce, Mg, and mixtures thereof.
 6. The method of claim 1, wherein thebarrier layer is transparent.
 7. A photoresist-free method of forming abarrier layer on a substrate, comprising the steps of: selecting atleast one precursor material; forming a layer comprising the unconvertedprecursor atop the substrate; exposing at least a portion of theunconverted precursor layer to electromagnetic radiation; substantiallyremoving at least a portion of the unconverted precursor layer to forman amorphous film with barrier layer properties; wherein said substrateis flexible.
 8. The method of claim 7, further comprising convertingwith an energy source selected from light, electron beam irradiation,ion beam irradiation, and mixtures thereof.
 9. The method of claim 8,further comprising substantially removing at least a portion of theunconverted precursor layer by using a developer.
 10. The method ofclaim 7, further comprising selecting the at least one precursormaterial from a metal complex comprising at least one ligand selectedfrom the group consisting of acac, carboxylato, alkoxy, azide, carbonyl,nitrato, amine, halide, nitro, and mixtures thereof and at least onemetal selected from the group consisting of Li, Al, Si, Ti, V, Cr, Mn,Fe, Ni, Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Ba, La,Pr, Sm, Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As, Ce, Mg,and mixtures thereof.
 11. A barrier layer for use in an organic lightemitting device formed by: selecting at least one precursor material;forming a layer comprising the unconverted precursor atop the substrate;exposing at least a portion of the unconverted precursor layer toelectromagnetic radiation; substantially removing at least a portion ofthe unconverted precursor layer to form an amorphous film withenvironmental barrier layer properties substantially preventing theingress of oxygen and water vapor from the environment.
 12. The barrierlayer of claim 11, further comprising converting with an energy sourceselected from light, electron beam irradiation, ion beam irradiation,and mixtures thereof.
 13. The barrier layer of claim 11, furthercomprising substantially removing at least a portion of the unconvertedprecursor layer by using a developer.
 14. The barrier layer of claim 11,further comprising selecting the at least one precursor material from ametal complex comprising at least one ligand selected from the groupconsisting of acac, carboxylato, alkoxy, azide, carbonyl, nitrato,amine, halide, nitro, and mixtures thereof and at least one metalselected from the group consisting of Li, Al, Si, Ti, V, Cr, Mn, Fe, Ni,Co, Cu, Zn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Ba, La, Pr, Sm,Eu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Pb, Th, U, Sb, As, Ce, Mg, andmixtures thereof.
 15. The barrier layer of claim 11 wherein saidsubstrate is flexible.
 16. The barrier layer of claim 11 wherein saidbarrier layer is transparent.
 17. The method of claim 1, wherein thebarrier layer is formed at about ambient temperature.
 18. The method ofclaim 7, wherein the barrier layer is formed at about ambienttemperature.
 19. The barrier layer of claim 11, wherein the barrierlayer is formed at about ambient temperature.
 20. The barrier layer ofclaim 11, wherein the barrier layer is TiO₂.